diff --git a/docs/xml/index.md b/docs/xml/index.md
index 82b4885..4a1dd19 100644
--- a/docs/xml/index.md
+++ b/docs/xml/index.md
@@ -37,7 +37,7 @@ Bibliographic citation
 
 This document provides guidelines for implementing application schemas based on [Darwin Core terms](../../terms/) using [XML](http://www.w3.org/XML/). The underlying metadata model is described (in a syntax neutral way), followed by some specific guidelines for XML implementations. Some guidance on the use of non-Darwin Core terms is also provided.
 
-This document does not provide guidelines for encoding Darwin Core in RDF/XML. Nor does it take a position on the relative merits of encoding metadata in "plain" XML rather than RDF/XML. This document provides guidelines in those cases where RDF/XML is not considered appropriate. For information about implementing Darwin Core as RDF, see the Darwin Core RDF Guide, <http://rs.tdwg.org/dwc/terms/guides/rdf/>.
+This document does not provide guidelines for encoding Darwin Core in RDF/XML. Nor does it take a position on the relative merits of encoding metadata in "plain" XML rather than RDF/XML. This document provides guidelines in those cases where RDF/XML is not considered appropriate.
 
 ### 1.1 Status of the content of this document
 
@@ -59,22 +59,21 @@ Implementors SHOULD base their XML applications on [XML Schemas](http://www.w3.o
 
 ### 2.2 XML namespaces
 
-Implementors SHOULD use [XML Namespaces](http://www.w3.org/TR/1999/REC-xml-names-19990114/) to uniquely identify elements. Darwin Core namespaces are defined in the [Darwin Core Namespace Policy](../../namespace/), while Dublin Core namespaces are defined in the [DCMI Namespace Recommendation](http://dublincore.org/documents/dcmi-namespace/).
+Implementors MUST use [XML Namespaces](http://www.w3.org/TR/1999/REC-xml-names-19990114/) to uniquely identify elements. Darwin Core namespaces are defined in the [Darwin Core Namespace Policy](../../namespace/), while Dublin Core namespaces are defined in the [DCMI Namespace Recommendation](http://dublincore.org/documents/dcmi-namespace/).
 
 ### 2.3 Abstract model
 
 The Darwin Core follows the [Dublin Core Metadata Initiative Abstract Model](http://dublincore.org/documents/abstract-model/) except that the Darwin Core _record_ is roughly equivalent to the Dublin Core _resource_.
 
-- Darwin Core terms are either `classes` or `properties`.
-- Each `property` has at most one `class` as its domain (describes no more than one `class`).
-- A `Darwin Core record` is made up of zero or more `classes` and one or more `properties` with their associated `values`.
-- Each `value` is a literal string.
+- Darwin Core terms MUST be either `classes` or `properties`.
+- A `Darwin Core record` MUST be made up of zero or more `classes` and one or more `properties` with their associated `values`.
+- Each `value` MUST be a literal string.
 - The `values` of `properties` within a `Darwin Core record` describe that record.
 - A `Darwin Core record` MUST include all required `properties`, if any, and their associated `values`.
 
 ### 2.4 Properties and values
 
-Darwin Core follows the guidelines for expressing [Dublin Core metadata using XML](http://dublincore.org/documents/dc-xml/) except in that Darwin Core implementors MUST encode `properties` as XML elements and `values` as the content of those elements instead of having each property contain a value representation and its associated value. The name of the XML element SHOULD be an XML qualified name (QName), which associates the value given in the `Term name` attribute in the [Darwin Core Terms](../../terms/) recommendation with the appropriate namespace name. For example, use:
+Darwin Core follows the guidelines for expressing [Dublin Core metadata using XML](http://dublincore.org/documents/dc-xml/) except in that Darwin Core implementors MUST encode `properties` as XML elements and `values` as the content of those elements instead of having each property contain a value representation and its associated value. The name of the XML element MUST be an XML qualified name (QName), which associates the value given in the `Term name` attribute in the [Darwin Core Terms](../../terms/) recommendation with the appropriate namespace name. For example, use:
 
 ```xml
 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
@@ -92,13 +91,13 @@ rather than:
 
 ### 2.5 Null values
 
-Elements for which the value is null SHOULD be omitted from the document or OPTIONALLY be explicitly coded using the attribute `xsi:nil="true"`.
+Elements for which the value is null SHOULD be omitted from the document or explicitly coded using the attribute `xsi:nil="true"`.
 
 ```xml
 <dwc:locality xsi:nil="true"/>
 ```
 
-Implementers MUST NOT use an empty string - an element with no content:
+An empty string - an element with no content - MUST NOT be used:
 
 ```xml
 <dwc:locality></dwc:locality>
@@ -106,235 +105,230 @@ Implementers MUST NOT use an empty string - an element with no content:
 
 ### 2.6 Simple Darwin Core
 
-[Simple Darwin Core](tdwg_dwc_simple.xsd) most closely models the "flat" nature of many data sets. It is a ready-made schema for sharing information with no structure beyond properties of a _record_ (equivalent to fields in a table, or columns in a spreadsheet). It is meant to accommodate all properties except those that require further structure to be meaningful (auxilliary terms in the classes [ResourceRelationship](http://rs.tdwg.org/dwc/terms/ResourceRelationship) and [MeasurementOrFact](http://rs.tdwg.org/dwc/terms/MeasurementOrFact). The schema has no required terms and terms SHOULD NOT be repeated within a given _record_. Refer to [Simple Darwin Core](../simple/) for the rationale behind this schema.
+[Simple Darwin Core](tdwg_dwc_simple.xsd) most closely models the "flat" nature of many data sets. It is a ready-made schema for sharing information with no structure beyond properties of a _record_ (equivalent to fields in a table, or columns in a spreadsheet). It is meant to accommodate all properties except those that require further structure to be meaningful (auxilliary terms in the classes [ResourceRelationship](http://rs.tdwg.org/dwc/terms/ResourceRelationship), [MeasurementOrFact](http://rs.tdwg.org/dwc/terms/MeasurementOrFact), and [ChronometricAge](http://rs.tdwg.org/chrono/terms/ChronometricAge). The schema has no required terms and no term is repeated within a given _record_. Refer to [Simple Darwin Core](../simple/) for the rationale behind this schema.
 
-The term [`dcterms:type`](http://rs.tdwg.org/dwc/terms/dcterms:type) (which is controlled by the [Dublin Core Type Vocabulary](http://dublincore.org/documents/dcmi-type-vocabulary/)), gives the basic category of object (`PhysicalObject`, `StillImage`, `MovingImage`, `Sound`, `Text`) the record is about. The term [`basisOfRecord`](http://rs.tdwg.org/dwc/terms/basisOfRecord), which has a controlled vocabulary distinct from that of `dcterms:type`, shows the name of the Darwin Core class (e.g., [`LivingSpecimen`](http://rs.tdwg.org/dwc/terms/LivingSpecimen), [`PreservedSpecimen`](http://rs.tdwg.org/dwc/terms/PreservedSpecimen), [`FossilSpecimen`](http://rs.tdwg.org/dwc/terms/FossilSpecimen), [`HumanObservation`](http://rs.tdwg.org/dwc/terms/HumanObservation), [`MachineObservation`](http://rs.tdwg.org/dwc/terms/MachineObservation), [`Taxon`](http://rs.tdwg.org/dwc/terms/Taxon)) the record is about.
+The term [`dcterms:type`](http://rs.tdwg.org/dwc/terms/dcterms:type) (which is controlled by the [Dublin Core Type Vocabulary](http://dublincore.org/documents/dcmi-type-vocabulary/)), gives the basic category of object (`PhysicalObject`, `StillImage`, `MovingImage`, `Sound`, `Text`) the record is about. The term [`basisOfRecord`](http://rs.tdwg.org/dwc/terms/basisOfRecord), which has a controlled vocabulary distinct from that of `dcterms:type`, shows the name of the Darwin Core class (e.g., [`LivingSpecimen`](http://rs.tdwg.org/dwc/terms/LivingSpecimen), [`PreservedSpecimen`](http://rs.tdwg.org/dwc/terms/PreservedSpecimen), [`FossilSpecimen`](http://rs.tdwg.org/dwc/terms/FossilSpecimen), [`MaterialCitation`](http://rs.tdwg.org/dwc/terms/MaterialCitation), [`HumanObservation`](http://rs.tdwg.org/dwc/terms/HumanObservation), [`MachineObservation`](http://rs.tdwg.org/dwc/terms/MachineObservation), [`Taxon`](http://rs.tdwg.org/dwc/terms/Taxon)) the record is about.
 
 #### 2.6.1 Simple Darwin Core example (non-normative)
 
-Following is a brief example of an XML document for a single specimen complying with the [Simple Darwin Core Schema](tdwg_dwc_simple.xsd)]. The [Simple Darwin Core XML example document](example_simple.xml) (if this link shows a blank page in your browser, use the View Source option to see the XML document) shows detail for a single record having a more complete set of elements.
+Following is a brief example of an XML document for a single specimen complying with the [Simple Darwin Core Schema](tdwg_dwc_simple.xsd)].
 
 ```xml
 <?xml version="1.0"?>
 <dwr:SimpleDarwinRecordSet
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://rs.tdwg.org/dwc/xsd/simpledarwincore/  http://rs.tdwg.org/dwc/xsd/tdwg_dwc_simple.xsd"
+    xmlns:dc="http://purl.org/dc/elements/1.1/"
     xmlns:dcterms="http://purl.org/dc/terms/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
     xmlns:dwr="http://rs.tdwg.org/dwc/xsd/simpledarwincore/">
     <dwr:SimpleDarwinRecord>
-        <dcterms:type>PhysicalObject</dcterms:type>
+        <dc:type>PhysicalObject</dc:type>
         <dcterms:modified>2009-02-12T12:43:31</dcterms:modified>
-        <dcterms:rightsHolder>Museum of Vertebrate Zoology</dcterms:rightsHolder>
-        <dcterms:rights>Creative Commons License</dcterms:rights>
-        <dwc:institutionCode>MVZ</dwc:institutionCode>
-        <dwc:collectionCode>Mammals</dwc:collectionCode>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14523</dwc:occurrenceID>
+        <dc:language>en</dc:language>
+        <dcterms:rightsHolder>Regents of the University of California</dcterms:rightsHolder>
+        <dcterms:license>http://creativecommons.org/publicdomain/zero/1.0/legalcode</dcterms:license>
         <dwc:basisOfRecord>PreservedSpecimen</dwc:basisOfRecord>
-        <dwc:country>Argentina</dwc:country>
-        <dwc:countryCode>AR</dwc:countryCode>
-        <dwc:stateProvince>Neuquén</dwc:stateProvince>
-        <dwc:locality>25 km al NNE de Bariloche por Ruta 40 (=237)</dwc:locality>
+        <dwc:institutionCode>MVZ</dwc:institutionCode>
+        <dwc:collectionCode>Mammal specimens</dwc:collectionCode>
+        <dwc:catalogNumber>MVZ:Mamm:14523</dwc:catalogNumber>
+        <dec:sex>male</dwc:sex>
+        <dwc:occurrenceID>http://arctos.database.museum/guid/MVZ:Mamm:14523?seid=770093</dwc:occurrenceID>
+        <dwc:country>United States</dwc:country>
+        <dwc:countryCode>US</dwc:countryCode>
+        <dwc:stateProvince>California</dwc:stateProvince>
+        <dwc:county>Kern County</dwc:county>
+        <dwc:locality>8 mi NE Bakersfield</dwc:locality>
+        <dwc:decimalLatitude>35.45038</dwc:decimalLatitude>
+        <dwc:decimalLongitude>-118.9092</dwc:decimalLongitude>
+        <dwc:geodeticDatum>epdg:4267</dwc:geodeticDatum>
+        <dwc:coordinateUncertaintyInMeters>13696</dwc:coordinateUncertaintyInMeters>
+        <dwc:eventDate>1911-05-14</dwc:eventDate>
+        <dwc:scientificName><Perognathus inornatus inornatus/dwc:scientificName>
     </dwr:SimpleDarwinRecord>
 </dwr:SimpleDarwinRecordSet>
 ```
 
 ### 2.7 Classes and containment
 
-Many Darwin Core terms (`properties`) are defined as being associated with another term (a `class`). For example, [`scientificName`](http://rs.tdwg.org/dwc/terms/scientificName) and [`Taxon`](http://rs.tdwg.org/dwc/terms/Taxon) are both Darwin Core terms, but `scientificName` is a property associated with the `Taxon` class. When constructing schemas that take advantage of classes in structures, implementors are encouraged to maintain the property/class relationships defined by the terms whenever possible (refer to the `Class` attribute of the term as given in the [Quick Reference Guide](../../terms/) or the attribute `dwcattributes:organizedInClass` in the term declaration in the [`dcterms.rdf`](../rdf/dcterms.rdf) file. To promote reuse, Darwin Core provides a set of xml schemas to use as the basis of additional schemas:
+Many Darwin Core terms (`properties`) are defined as being associated with another term (a `class`). For example, [`scientificName`](http://rs.tdwg.org/dwc/terms/scientificName) and [`Taxon`](http://rs.tdwg.org/dwc/terms/Taxon) are both Darwin Core terms, but `scientificName` is a property organized within the `Taxon` class. When constructing schemas that take advantage of classes in structures, implementors SHOULD maintain the property/class organization for the terms whenever possible (refer to the grouping of the term within a class in the [Quick Reference Guide](../../terms/). To promote reuse, Darwin Core provides a set of xml schemas to use as the basis of additional schemas:
 
 - [Terms XML Schema](tdwg_dwcterms.xsd) - property term definitions as typed global elements and named groups for all terms for a given class to be referenced. The schema makes use of substitution groups `anyClass`, `anyProperty`, `anyIdentifier` and `anyXYZTerm` for each class, e.g. `anyTaxonTerm`. This is the schema upon which the [Simple Darwin Core XML Schema](tdwg_dwc_simple.xsd) is based.
 - [Class Terms XML Schema](tdwg_dwc_class_terms.xsd) - class term definitions as typed global elements with subelements referencing all corresponding property terms via their substitution group.
 
-It is RECOMMENDED to use classes in a normalized way to avoid deep nesting. A [Darwin Core Tools and Applications page](https://github.com/tdwg/dwc-documentation/blob/master/documentation/resources.md) has been created as an index to example schemas for the purpose of community discussions and development. An [XML schema](tdwg_dwc_classes.xsd) is provided to freely mix any Darwin Core Class in a global list and allow them to reference each other using the respective class identifier terms.
+Classes SHOULD be used in a normalized way to avoid deep nesting. An [XML schema](tdwg_dwc_classes.xsd) is provided to freely mix any Darwin Core Class in a global list and allow them to reference each other using the respective class identifier terms.
 
 #### 2.7.1 Normalized classes examples (non-normative)
 
-Following is an example of using normalized classes to represent two related specimen occurrences (one of which has had a second identification) at one location following this class-based schema. Note that you can reuse the location definition here by referring to it via locationID:
+Following is an example of using a normalized class-based schema to represent two related specimen occurrences from one Event. In this example a Western garter snake collected by Gordon W Gullion in 1949 was found to have eaten a Coastal giant salamander. Note the reuse of class instances by referring to the identifiers declared in the instances of those classes:
 
 ```xml
-<?xml version="1.0"?>
-<dwr:DarwinRecordSet
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://rs.tdwg.org/dwc/dwcrecord/  http://rs.tdwg.org/dwc/xsd/tdwg_dwc_classes.xsd"
-    xmlns:dcterms="http://purl.org/dc/terms/"
-    xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
-    xmlns:dwr="http://rs.tdwg.org/dwc/dwcrecord/">
-    <dcterms:Location>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-        <dwc:country>Argentina</dwc:country>
-        <dwc:countryCode>AR</dwc:countryCode>
-        <dwc:stateProvince>Neuquén</dwc:stateProvince>
-        <dwc:locality>25 km al NNE de Bariloche por Ruta 40 (=237)</dwc:locality>
-    </dcterms:Location>
-    <dwc:Occurrence>
-        <dcterms:type>PhysicalObject</dcterms:type>
-        <dcterms:modified>2009-02-12T12:43:31</dcterms:modified>
-        <dwc:institutionCode>MVZ</dwc:institutionCode>
-        <dwc:collectionCode>Mammals</dwc:collectionCode>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14523</dwc:occurrenceID>
-        <dwc:basisOfRecord>PreservedSpecimen</dwc:basisOfRecord>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-    </dwc:Occurrence>
-    <dwc:Identification>
-        <dwc:identificationID>http://guid.mvz.org/identifications/23459</dwc:identificationID>
-        <dwc:identifiedBy>Richard Sage</dwc:identifiedBy>
-        <dwc:dateIdentified>2000</dwc:dateIdentified>
-        <dwc:identificationQualifier>sp.</dwc:identificationQualifier>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14523</dwc:occurrenceID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:d79c11aa-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Identification>
-    <dwc:Taxon>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:d79c11aa-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-        <dwc:scientificName>Ctenomys</dwc:scientificName>
-        <dwc:taxonRank>genus</dwc:taxonRank>
-        <dwc:nomenclaturalCode>ICZN</dwc:nomenclaturalCode>
-        <dwc:genus>Ctenomys</dwc:genus>
-    </dwc:Taxon>
-    <dwc:Identification>
-        <dwc:identificationID>http://guid.mvz.org/identifications/94752</dwc:identificationID>
-        <dwc:identifiedBy>James L Patton</dwc:identifiedBy>
-        <dwc:dateIdentified>2001-09-14</dwc:dateIdentified>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14523</dwc:occurrenceID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:df0a797c-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Identification>
-    <dwc:Taxon>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:df0a797c-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-        <dwc:parentNameUsageID>urn:lsid:catalogueoflife.org:taxon:d79c11aa-29c1-102b-9a4a-00304854f820:col20120721</dwc:parentNameUsageID>
-        <dwc:scientificName>Ctenomys sociabilis</dwc:scientificName>
-        <dwc:scientificNameAuthorship>Pearson and Christie, 1985</dwc:scientificNameAuthorship>
-        <dwc:taxonRank>species</dwc:taxonRank>
-        <dwc:nomenclaturalCode>ICZN</dwc:nomenclaturalCode>
-        <dwc:higherClassification>Animalia; Chordata; Vertebrata; Mammalia; Theria; Eutheria; Rodentia; Hystricognatha; Hystricognathi; Ctenomyidae; Ctenomyini; Ctenomys</dwc:higherClassification>
-        <dwc:kingdom>Animalia</dwc:kingdom>
-        <dwc:phylum>Chordata</dwc:phylum>
-        <dwc:class>Mammalia</dwc:class>
-        <dwc:order>Rodentia</dwc:order>
-        <dwc:family>Ctenomyidae</dwc:family>
-        <dwc:genus>Ctenomys</dwc:genus>
-        <dwc:specificEpithet>sociabilis</dwc:specificEpithet>
-    </dwc:Taxon>
-    <dwc:Occurrence>
-        <dcterms:type>PhysicalObject</dcterms:type>
-        <dcterms:modified>2009-02-12T12:43:31</dcterms:modified>
-        <dwc:institutionCode>MVZ</dwc:institutionCode>
-        <dwc:collectionCode>Mammals</dwc:collectionCode>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14524</dwc:occurrenceID>
-        <dwc:basisOfRecord>PreservedSpecimen</dwc:basisOfRecord>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-    </dwc:Occurrence>
-    <dwc:Identification>
-        <dwc:identificationID>http://guid.mvz.org/identifications/94753</dwc:identificationID>
-        <dwc:identifiedBy>James L Patton</dwc:identifiedBy>
-        <dwc:dateIdentified>2001-09-14</dwc:dateIdentified>
-        <dwc:occurrenceID>urn:catalog:MVZ:Mammals:14524</dwc:occurrenceID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:df0a797c-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Identification>
-    <dwc:ResourceRelationship>
-        <dwc:resourceRelationshipID>http://guid.mvz.org/relations/23423</dwc:resourceRelationshipID>
-        <dwc:resourceID>urn:catalog:MVZ:Mammals:14523</dwc:resourceID>
-        <dwc:relatedResourceID>urn:catalog:MVZ:Mammals:14524</dwc:relatedResourceID>
-        <dwc:relationshipOfResource>offspring of</dwc:relationshipOfResource>
-    </dwc:ResourceRelationship>
-    <dwc:ResourceRelationship>
-        <dwc:resourceRelationshipID>http://guid.mvz.org/relations/23424</dwc:resourceRelationshipID>
-        <dwc:resourceID>urn:catalog:MVZ:Mammals:14524</dwc:resourceID>
-        <dwc:relatedResourceID>urn:catalog:MVZ:Mammals:14523</dwc:relatedResourceID>
-        <dwc:relationshipOfResource>mother of</dwc:relationshipOfResource>
-    </dwc:ResourceRelationship>
-</dwr:DarwinRecordSet>
-```
+<?xml version="1.0" encoding="UTF-8"?>
+<dwr:DarwinRecordSet xmlns:dwr="http://rs.tdwg.org/dwc/dwcrecord/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:dwc="http://rs.tdwg.org/dwc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://rs.tdwg.org/dwc/dwcrecord/  http://rs.tdwg.org/dwc/xsd/tdwg_dwc_classes.xsd">
+   <dwc:Occurrence>
+      <dwc:occurrenceID>http://arctos.database.museum/guid/MVZ:Herp:51568?seid=525813</dwc:occurrenceID>
+      <dcterms:type>PhysicalObject</dcterms:type>
+      <dwc:basisOfRecord>PreservedSpecimen</dwc:basisOfRecord>
+      <dwc:institutionCode>MVZ</dwc:institutionCode>
+      <dwc:collectionCode>Amphibian and reptile specimens</dwc:collectionCode>
+      <dwc:catalogNumber>MVZ:Herp:51568</dwc:catalogNumber>
+      <dwc:recordedBy>Gordon W. Gullion</dwc:recordedBy>
+      <dwc:organismID>http://arctos.database.museum/guid/MVZ:Herp:51568</dwc:organismID>
+      <dwc:eventID>525813</dwc:eventID>
+      <dwc:associatedMedia>http://arctos.database.museum/MediaSearch.cfm?collection_object_id=10513964</dwc:associatedMedia>
+      <dwc:associatedOccurrences>"had stomach contents":"http://arctos.database.museum/guid/MVZ:Herp:51500?seid=670405"</dwc:associatedOccurrences>
+   </dwc:Occurrence>
+   <dwc:Organism>
+      <dwc:organismID>http://arctos.database.museum/guid/MVZ:Herp:51568</dwc:organismID>
+      <dwc:organismScope>multicellular organism</dwc:organismScope>
+      <dwc:associatedOrganisms>"ate":"http://arctos.database.museum/guid/MVZ:Herp:51500"</dwc:associatedOrganisms>
+   </dwc:Organism>
+   <dwc:Event>
+      <dwc:eventID>525813</dwc:eventID>
+      <dwc:eventDate>1949-09-02</dwc:eventDate>
+      <dwc:verbatimEventDate>2 Sep 1949</dwc:verbatimEventDate>
+      <dwc:locationID>https://arctos.database.museum/place.cfm?action=detail&amp;locality_id=10754971</dwc:locationID>
+   </dwc:Event>
+   <dcterms:Location>
+      <dwc:locationID>https://arctos.database.museum/place.cfm?action=detail&amp;locality_id=10754971</dwc:locationID>
+      <dwc:country>United States</dwc:country>
+      <dwc:countryCode>US</dwc:countryCode>
+      <dwc:stateProvince>California</dwc:stateProvince>
+      <dwc:county>Humboldt County</dwc:county>
+      <dwc:locality>Raccoon Creek, 3 mi N Willow Creek</dwc:locality>
+   </dcterms:Location>
+   <dwc:Identification>
+      <dwc:identifiedBy>Museum of Vertebrate Zoology, University of California, Berkeley</dwc:identifiedBy>
+      <dwc:dateIdentified>1999-01-27</dwc:dateIdentified>
+      <dwc:occurrenceID>http://arctos.database.museum/guid/MVZ:Herp:51568?seid=525813</dwc:occurrenceID>
+      <dwc:taxonID>https://www.gbif.org/species/2457545</dwc:taxonID>
+   </dwc:Identification>
+   <dwc:Taxon>
+      <dwc:taxonID>https://www.gbif.org/species/2457545</dwc:taxonID>
+      <dwc:scientificName>Thamnophis elegans (Baird &amp; Girard, 1853)</dwc:scientificName>
+      <dwc:taxonRank>species</dwc:taxonRank>
+      <dwc:genus>Thamnophis</dwc:genus>
+      <dwc:specificEpithet>elgans</dwc:specificEpithet>
+   </dwc:Taxon>
+   <dwc:Occurrence>
+      <dwc:occurrenceID>http://arctos.database.museum/guid/MVZ:Herp:51500?seid=670405</dwc:occurrenceID>
+      <dcterms:type>PhysicalObject</dcterms:type>
+      <dwc:basisOfRecord>PreservedSpecimen</dwc:basisOfRecord>
+      <dwc:institutionCode>MVZ</dwc:institutionCode>
+      <dwc:collectionCode>Amphibian and reptile specimens</dwc:collectionCode>
+      <dwc:catalogNumber>MVZ:Herp:51500</dwc:catalogNumber>
+      <dwc:recordedBy>Gordon W. Gullion</dwc:recordedBy>
+      <dwc:eventID>525813</dwc:eventID>
+      <dwc:associatedMedia>http://arctos.database.museum/MediaSearch.cfm?collection_object_id=10513964</dwc:associatedMedia>
+      <dwc:associatedOccurrences>"found as stomach contents of":"http://arctos.database.museum/guid/MVZ:Herp:51568?seid=525813"</dwc:associatedOccurrences>
+   </dwc:Occurrence>
+   <dwc:Organism>
+      <dwc:organismID>http://arctos.database.museum/guid/MVZ:Herp:51500</dwc:organismID>
+      <dwc:organismScope>multicellular organism</dwc:organismScope>
+      <dwc:associatedOrganisms>"eaten by":"http://arctos.database.museum/guid/MVZ:Herp:51568"</dwc:associatedOrganisms>
+   </dwc:Organism>
+   <dwc:Identification>
+      <dwc:identifiedBy>Museum of Vertebrate Zoology, University of California, Berkeley</dwc:identifiedBy>
+      <dwc:dateIdentified>1999-01-27</dwc:dateIdentified>
+      <dwc:occurrenceID>http://arctos.database.museum/guid/MVZ:Herp:51500?seid=670405</dwc:occurrenceID>
+      <dwc:taxonID>https://www.gbif.org/species/2432022</dwc:taxonID>
+   </dwc:Identification>
+   <dwc:Taxon>
+      <dwc:taxonID>https://www.gbif.org/species/2432022</dwc:taxonID>
+      <dwc:scientificName>Dicamptodon tenebrosus (Baird &amp; Girard, 1852)</dwc:scientificName>
+      <dwc:taxonRank>species</dwc:taxonRank>
+      <dwc:genus>Dicamptodon</dwc:genus>
+      <dwc:specificEpithet>tenebrosus</dwc:specificEpithet>
+   </dwc:Taxon>
+   <dwc:ResourceRelationship>
+      <dwc:resourceID>http://arctos.database.museum/guid/MVZ:Herp:51568</dwc:resourceID>
+      <dwc:relationshipOfResource>ate</dwc:relationshipOfResource>
+      <dwc:relatedResourceID>http://arctos.database.museum/guid/MVZ:Herp:51500</dwc:relatedResourceID>
+   </dwc:ResourceRelationship>
+   <dwc:ResourceRelationship>
+      <dwc:resourceID>http://arctos.database.museum/guid/MVZ:Herp:51500</dwc:resourceID>
+      <dwc:relationshipOfResource>eaten by</dwc:relationshipOfResource>
+      <dwc:relatedResourceID>http://arctos.database.museum/guid/MVZ:Herp:51568</dwc:relatedResourceID>
+   </dwc:ResourceRelationship>
+</dwr:DarwinRecordSet>```
 
-Here is different example demonstrating area count observations for events on two different days at one location. Note that we omit the identification class here as there is not identification related data and link via the `taxonID` directly:
+Here is an example demonstrating area count observations for Events on two different days at the same location. Note that we omit the identification class here as there is no identification-related data and link directly to the Taxon via the `taxonID`:
 
 ```xml
-<?xml version="1.0"?>
-<dwr:DarwinRecordSet
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://rs.tdwg.org/dwc/dwcrecord/  http://rs.tdwg.org/dwc/xsd/tdwg_dwc_classes.xsd"
-    xmlns:dcterms="http://purl.org/dc/terms/"
-    xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
-    xmlns:dwr="http://rs.tdwg.org/dwc/dwcrecord/">
-    <dcterms:Location>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-        <dwc:country>Argentina</dwc:country>
-        <dwc:countryCode>AR</dwc:countryCode>
-        <dwc:stateProvince>Neuquén</dwc:stateProvince>
-        <dwc:locality>Valle Limay, Estancia Rincon Grande, 48 ha area with centroid at this point</dwc:locality>
-        <dwc:decimalLatitude>-40.97467</dwc:decimalLatitude>
-        <dwc:decimalLongitude>-71.0734</dwc:decimalLongitude>
-        <dwc:geodeticDatum>WGS84</dwc:geodeticDatum>
-        <dwc:coordinateUncertaintyInMeters>200</dwc:coordinateUncertaintyInMeters>
-    </dcterms:Location>
-    <dwc:Event>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/26/17</dwc:eventID>
-        <dwc:samplingProtocol>area count</dwc:samplingProtocol>
-        <dwc:eventDate>2006-11-26</dwc:eventDate>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-    </dwc:Event>
-    <dwc:Occurrence>
-        <dwc:occurrenceID>urn:catalog:AUDCLO:EBIRD:OBS64515288</dwc:occurrenceID>
-        <dcterms:type>Event</dcterms:type>
-        <dcterms:modified>2009-02-17T07:33:04Z</dcterms:modified>
-        <dwc:institutionCode>AUDCLO</dwc:institutionCode>
-        <dwc:collectionCode>EBIRD</dwc:collectionCode>
-        <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
-        <dwc:individualCount>2</dwc:individualCount>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/26/17</dwc:eventID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000ee00-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Occurrence>
-    <dwc:Taxon>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000ee00-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-        <dwc:scientificName>Anthus hellmayri Hartert, 1909</dwc:scientificName>
-        <dwc:class>Aves</dwc:class>
-        <dwc:genus>Anthus</dwc:genus>
-        <dwc:specificEpithet>hellmayri</dwc:specificEpithet>
-    </dwc:Taxon>
-    <dwc:Occurrence>
-        <dwc:occurrenceID>urn:catalog:AUDCLO:EBIRD:OBS64515286</dwc:occurrenceID>
-        <dcterms:type>Event</dcterms:type>
-        <dcterms:modified>2009-02-17T07:33:04Z</dcterms:modified>
-        <dwc:institutionCode>AUDCLO</dwc:institutionCode>
-        <dwc:collectionCode>EBIRD</dwc:collectionCode>
-        <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
-        <dwc:individualCount>1</dwc:individualCount>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/26/17</dwc:eventID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000e838-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Occurrence>
-    <dwc:Taxon>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000e838-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-        <dwc:scientificName>Anthus correndera Vieillot, 1818</dwc:scientificName>
-        <dwc:class>Aves</dwc:class>
-        <dwc:genus>Anthus</dwc:genus>
-        <dwc:specificEpithet>correndera</dwc:specificEpithet>
-    </dwc:Taxon>
-    <dwc:Event>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/27/6</dwc:eventID>
-        <dwc:samplingProtocol>area count</dwc:samplingProtocol>
-        <dwc:eventDate>2006-11-27</dwc:eventDate>
-        <dwc:locationID>http://guid.mvz.org/sites/arg/127</dwc:locationID>
-    </dwc:Event>
-    <dwc:Occurrence>
-        <dwc:occurrenceID>urn:catalog:AUDCLO:EBIRD:OBS64515333</dwc:occurrenceID>
-        <dcterms:type>Event</dcterms:type>
-        <dcterms:modified>2009-02-17T07:33:04Z</dcterms:modified>
-        <dwc:institutionCode>AUDCLO</dwc:institutionCode>
-        <dwc:collectionCode>EBIRD</dwc:collectionCode>
-        <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
-        <dwc:individualCount>1</dwc:individualCount>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/27/6</dwc:eventID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000ee00-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Occurrence>
-    <dwc:Occurrence>
-        <dwc:occurrenceID>urn:catalog:AUDCLO:EBIRD:OBS64515331</dwc:occurrenceID>
-        <dcterms:type>Event</dcterms:type>
-        <dcterms:modified>2009-02-17T07:33:04Z</dcterms:modified>
-        <dwc:institutionCode>AUDCLO</dwc:institutionCode>
-        <dwc:collectionCode>EBIRD</dwc:collectionCode>
-        <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
-        <dwc:individualCount>2</dwc:individualCount>
-        <dwc:eventID>http://guid.mvz.org/events/2006/11/27/6</dwc:eventID>
-        <dwc:taxonID>urn:lsid:catalogueoflife.org:taxon:f000ee00-29c1-102b-9a4a-00304854f820:col20120721</dwc:taxonID>
-    </dwc:Occurrence>
+<?xml version="1.0" encoding="UTF-8"?>
+<dwr:DarwinRecordSet xmlns:dwr="http://rs.tdwg.org/dwc/dwcrecord/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:dwc="http://rs.tdwg.org/dwc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://rs.tdwg.org/dwc/dwcrecord/  http://rs.tdwg.org/dwc/xsd/tdwg_dwc_classes.xsd">
+   <dcterms:Location>
+      <dwc:locationID>AR-NQ-LL-ERG</dwc:locationID>
+      <dwc:country>Argentina</dwc:country>
+      <dwc:countryCode>AR</dwc:countryCode>
+      <dwc:stateProvince>Neuquén</dwc:stateProvince>
+      <dwc:locality>Valle Limay, Estancia Rincon Grande, 48 ha area with centroid at this point</dwc:locality>
+      <dwc:decimalLatitude>-40.97467</dwc:decimalLatitude>
+      <dwc:decimalLongitude>-71.0734</dwc:decimalLongitude>
+      <dwc:geodeticDatum>WGS84</dwc:geodeticDatum>
+      <dwc:coordinateUncertaintyInMeters>200</dwc:coordinateUncertaintyInMeters>
+   </dcterms:Location>
+   <dwc:Event>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/26</dwc:eventID>
+      <dwc:samplingProtocol>area count</dwc:samplingProtocol>
+      <dwc:eventDate>2006-11-26</dwc:eventDate>
+      <dwc:locationID>AR-NQ-LL-ERG</dwc:locationID>
+   </dwc:Event>
+   <dwc:Occurrence>
+      <dwc:occurrenceID>URN:catalog:CLO:EBIRD:OBS64515288</dwc:occurrenceID>
+      <dwc:institutionCode>CLO</dwc:institutionCode>
+      <dwc:collectionCode>EBIRD</dwc:collectionCode>
+      <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
+      <dwc:individualCount>2</dwc:individualCount>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/26</dwc:eventID>
+      <dwc:taxonID>https://www.gbif.org/species/2490280</dwc:taxonID>
+   </dwc:Occurrence>
+   <dwc:Taxon>
+      <dwc:taxonID>https://www.gbif.org/species/2490280</dwc:taxonID>
+      <dwc:scientificName>Anthus hellmayri Hartert, 1909</dwc:scientificName>
+      <dwc:class>Aves</dwc:class>
+      <dwc:genus>Anthus</dwc:genus>
+      <dwc:specificEpithet>hellmayri</dwc:specificEpithet>
+   </dwc:Taxon>
+   <dwc:Occurrence>
+      <dwc:occurrenceID>URN:catalog:CLO:EBIRD:OBS64515286</dwc:occurrenceID>
+      <dwc:institutionCode>CLO</dwc:institutionCode>
+      <dwc:collectionCode>EBIRD</dwc:collectionCode>
+      <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
+      <dwc:individualCount>4</dwc:individualCount>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/26</dwc:eventID>
+      <dwc:taxonID>https://www.gbif.org/species/9286490</dwc:taxonID>
+   </dwc:Occurrence>
+   <dwc:Taxon>
+      <dwc:taxonID>https://www.gbif.org/species/9286490</dwc:taxonID>
+      <dwc:scientificName>Anthus correndera Vieillot, 1818</dwc:scientificName>
+      <dwc:class>Aves</dwc:class>
+      <dwc:genus>Anthus</dwc:genus>
+      <dwc:specificEpithet>correndera</dwc:specificEpithet>
+   </dwc:Taxon>
+   <dwc:Event>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/27</dwc:eventID>
+      <dwc:samplingProtocol>area count</dwc:samplingProtocol>
+      <dwc:eventDate>2006-11-27</dwc:eventDate>
+      <dwc:locationID>AR-NQ-LL-ERG</dwc:locationID>
+   </dwc:Event>
+   <dwc:Occurrence>
+      <dwc:occurrenceID>URN:catalog:CLO:EBIRD:OBS64515333</dwc:occurrenceID>
+      <dwc:institutionCode>CLO</dwc:institutionCode>
+      <dwc:collectionCode>EBIRD</dwc:collectionCode>
+      <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
+      <dwc:individualCount>2</dwc:individualCount>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/27</dwc:eventID>
+      <dwc:taxonID>https://www.gbif.org/species/2490280</dwc:taxonID>
+   </dwc:Occurrence>
+   <dwc:Occurrence>
+      <dwc:occurrenceID>urn:catalog:AUDCLO:EBIRD:OBS64515331</dwc:occurrenceID>
+      <dwc:institutionCode>CLO</dwc:institutionCode>
+      <dwc:collectionCode>EBIRD</dwc:collectionCode>
+      <dwc:basisOfRecord>HumanObservation</dwc:basisOfRecord>
+      <dwc:individualCount>4</dwc:individualCount>
+      <dwc:eventID>JW-AR-NQ-LL-ERG/2006/11/27</dwc:eventID>
+      <dwc:taxonID>https://www.gbif.org/species/9286490</dwc:taxonID>
+   </dwc:Occurrence>
 </dwr:DarwinRecordSet>
 ```
diff --git a/docs/xml/tdwg_basetypes.xsd b/docs/xml/tdwg_basetypes.xsd
index 59da2a4..ac1db24 100644
--- a/docs/xml/tdwg_basetypes.xsd
+++ b/docs/xml/tdwg_basetypes.xsd
@@ -13,6 +13,7 @@
 <!-- Schema                                                               -->
 <!-- ==================================================================== -->
 <xs:schema 
+    version="2021-07-15"
 	xmlns:xs="http://www.w3.org/2001/XMLSchema"
 	elementFormDefault="unqualified" version="0.5">
 
@@ -76,13 +77,14 @@
         <xs:simpleType name="dateTimeISO">
           <xs:annotation>
             <xs:documentation xml:lang="en">
-              The date and time expressed in a way conforming to a subset of ISO 8601. Meant to be exactly the same as DateTimeISO defined in ABCD.
+              The date and time expressed in a way conforming to a subset of ISO 8601. 
+              Meant to be exactly the same as DateTimeISO defined in ABCD.
             </xs:documentation>
           </xs:annotation>
           <xs:restriction base="xs:string">
-            <xs:pattern value="\d\d\d\d(\-(0[1-9]|1[012])(\-((0[1-9])|1\d|2\d|3[01])(T(0\d|1\d|2[0-3])(:[0-5]\d){0,2})?)?)?|\-\-(0[1-9]|1[012])(\-(0[1-9]|1\d|2\d|3[01]))?|\-\-\-(0[1-9]|1\d|2\d|3[01])">
+            <xs:pattern 
+               value="\d\d\d\d(\-(0[1-9]|1[012])(\-((0[1-9])|1\d|2\d|3[01])(T(0\d|1\d|2[0-3])(:[0-5]\d){0,2})?)?)?|\-\-(0[1-9]|1[012])(\-(0[1-9]|1\d|2\d|3[01]))?|\-\-\-(0[1-9]|1\d|2\d|3[01])">
             </xs:pattern>
           </xs:restriction>
        </xs:simpleType>
-
 </xs:schema>
diff --git a/docs/xml/tdwg_dwc_class_terms.xsd b/docs/xml/tdwg_dwc_class_terms.xsd
index 27f26c5..696890a 100644
--- a/docs/xml/tdwg_dwc_class_terms.xsd
+++ b/docs/xml/tdwg_dwc_class_terms.xsd
@@ -1,14 +1,17 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<xs:schema version="2014-11-08" xmlns:xs="http://www.w3.org/2001/XMLSchema"
+<xs:schema 
+    version="2021-07-15" 
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="http://rs.tdwg.org/dwc/terms/"
+    xmlns:chrono="http://rs.tdwg.org/chrono/terms/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/">
     <xs:include schemaLocation="tdwg_dwcterms.xsd"/>
     
     <xs:annotation>
         <xs:documentation>
-            This schema redefines all darwin core classes to disallow compound 
-            objects - within a class no other nested class is allowed. It 
-            allows properties to occur in any order and as many times as needed.
+            This schema redefines all Darwin Core classes to disallow compound objects - 
+            within a class no other nested class is allowed. It allows properties to 
+            occur in any order and as many times as needed.
         </xs:documentation>
     </xs:annotation>
 
@@ -57,8 +60,6 @@
     </xs:element>
     
     <!-- LOCATION domain -->
-    <!-- reuses the dcterms:location term, so see dublin_core.xsd for definition -->
-    <!-- 
     <xs:element name="Location" substitutionGroup="dwc:anyClass">
         <xs:complexType>
             <xs:choice maxOccurs="unbounded">
@@ -68,7 +69,6 @@
             </xs:choice>
         </xs:complexType>
     </xs:element>  
-    -->
     
     <!-- GEOLOGICALCONTEXT domain -->
     <xs:element name="GeologicalContext" substitutionGroup="dwc:anyClass">
@@ -103,17 +103,6 @@
         </xs:complexType>
     </xs:element>
 
-    <!-- RESOURCE RELATIONSHIP domain -->
-    <xs:element name="ResourceRelationship" substitutionGroup="dwc:anyClass">
-        <xs:complexType>
-            <xs:choice maxOccurs="unbounded">
-                <xs:element ref="dwc:anyIdentifier"/>
-                <xs:element ref="dwc:anyResourceRelationshipTerm"/>
-                <xs:element ref="dwc:anyRecordLevelTerm"/>
-            </xs:choice>
-        </xs:complexType>
-    </xs:element>
-    
     <!-- MEASUREMENTORFACT domain -->
     <xs:element name="MeasurementOrFact" substitutionGroup="dwc:anyClass">
         <xs:complexType>
@@ -125,4 +114,25 @@
         </xs:complexType>
     </xs:element>
     
+    <!-- RESOURCE RELATIONSHIP domain -->
+    <xs:element name="ResourceRelationship" substitutionGroup="dwc:anyClass">
+        <xs:complexType>
+            <xs:choice maxOccurs="unbounded">
+                <xs:element ref="dwc:anyIdentifier"/>
+                <xs:element ref="dwc:anyResourceRelationshipTerm"/>
+                <xs:element ref="dwc:anyRecordLevelTerm"/>
+            </xs:choice>
+        </xs:complexType>
+    </xs:element>
+    
+    <!-- CHRONOMETRIC AGE domain -->
+    <xs:element name="ChronometricAge" substitutionGroup="dwc:anyClass">
+        <xs:complexType>
+            <xs:choice maxOccurs="unbounded">
+                <xs:element ref="dwc:anyIdentifier"/>
+                <xs:element ref="dwc:anyChronometricAgeTerm"/>
+                <xs:element ref="dwc:anyRecordLevelTerm"/>
+            </xs:choice>
+        </xs:complexType>
+    </xs:element>    
 </xs:schema>
\ No newline at end of file
diff --git a/docs/xml/tdwg_dwc_classes.xsd b/docs/xml/tdwg_dwc_classes.xsd
index 77899eb..4b59f4a 100644
--- a/docs/xml/tdwg_dwc_classes.xsd
+++ b/docs/xml/tdwg_dwc_classes.xsd
@@ -1,14 +1,18 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<xs:schema version="0.1" xmlns:xs="http://www.w3.org/2001/XMLSchema"
+<xs:schema 
+    version="2021-07-15" 
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="http://rs.tdwg.org/dwc/dwcrecord/"
     xmlns:dwr="http://rs.tdwg.org/dwc/dwcrecord/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/">
-    <xs:import namespace="http://rs.tdwg.org/dwc/terms/" schemaLocation="tdwg_dwc_class_terms.xsd"/>
+    <xs:import 
+       namespace="http://rs.tdwg.org/dwc/terms/" 
+       schemaLocation="tdwg_dwc_class_terms.xsd"/>
         
     <xs:annotation>
         <xs:documentation>
-            This schema defines a container for all darwin core classes with no notion of a record per se.
-            All classes are treated equally.
+            This schema defines a container for all Darwin Core classes with no notion 
+            of a record per se. All classes are treated equally.
         </xs:documentation>
     </xs:annotation>
     
@@ -19,5 +23,4 @@
             </xs:sequence>
         </xs:complexType>
     </xs:element>
-    
 </xs:schema>
diff --git a/docs/xml/tdwg_dwc_extensions.xsd b/docs/xml/tdwg_dwc_extensions.xsd
index f0ed398..3929d33 100644
--- a/docs/xml/tdwg_dwc_extensions.xsd
+++ b/docs/xml/tdwg_dwc_extensions.xsd
@@ -1,11 +1,15 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<xs:schema version="2014-11-08" 
+<xs:schema 
+    version="2021-07-15" 
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="http://rs.tdwg.org/dwc/terms/"
     xmlns:simple="http://rs.tdwg.org/dwc/xsd/simpledarwincore/"
+    xmlns:chrono="http://rs.tdwg.org/chrono/terms/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/">
     <xs:include schemaLocation="tdwg_dwcterms.xsd"/>
-    <xs:import namespace="http://rs.tdwg.org/dwc/xsd/simpledarwincore/" schemaLocation="tdwg_dwc_simple.xsd"/>
+    <xs:import 
+       namespace="http://rs.tdwg.org/dwc/xsd/simpledarwincore/" 
+       schemaLocation="tdwg_dwc_simple.xsd"/>
     
     <xs:annotation>
         <xs:documentation>
@@ -35,8 +39,10 @@
         <xs:complexType>
             <xs:all>
                 <xs:element ref="dwc:resourceRelationshipID" minOccurs="0"/>
+                <xs:element ref="dwc:resourceID" minOccurs="1"/>
+                <xs:element ref="dwc:relationshipOfResourceID" minOccurs="0"/>
                 <xs:element ref="dwc:relatedResourceID" minOccurs="1"/>
-                <xs:element ref="dwc:relationshipOfResource" minOccurs="1"/>
+                <xs:element ref="dwc:relationshipOfResource" minOccurs="0"/>
                 <xs:element ref="dwc:relationshipAccordingTo" minOccurs="0"/>
                 <xs:element ref="dwc:relationshipEstablishedDate" minOccurs="0"/>
                 <xs:element ref="dwc:relationshipRemarks" minOccurs="0"/>
@@ -44,4 +50,29 @@
         </xs:complexType>
     </xs:element>
     
+    <!-- CHRONOMETRIC AGE -->
+    <xs:element name="ChronometricAge" substitutionGroup="simple:anyExtension">
+        <xs:complexType>
+            <xs:all>
+                <xs:element ref="chrono:chronometricAgeID" minOccurs="0"/>
+                <xs:element ref="chrono:verbatimChronometricAge" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeProtocol" minOccurs="0"/>
+                <xs:element ref="chrono:uncalibratedChronometricAge" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeConversionProtocol" minOccurs="0"/>
+                <xs:element ref="chrono:earliestChronometricAge" minOccurs="0"/>
+                <xs:element ref="chrono:earliestChronometricReferenceSystem" minOccurs="0"/>
+                <xs:element ref="chrono:latestChronometricAge" minOccurs="0"/>
+                <xs:element ref="chrono:latestChronometricAgeReferenceSystem" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeUncertaintyInYears" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeUncertaintyMethod" minOccurs="0"/>
+                <xs:element ref="chrono:materialDated" minOccurs="0"/>
+                <xs:element ref="chrono:materialDatedID" minOccurs="0"/>
+                <xs:element ref="chrono:materialDatedRelationship" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeDeterminedBy" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeDeterminedDate" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeReferences" minOccurs="0"/>
+                <xs:element ref="chrono:chronometricAgeRemarks" minOccurs="0"/>
+            </xs:all>
+        </xs:complexType>
+    </xs:element>    
 </xs:schema>
\ No newline at end of file
diff --git a/docs/xml/tdwg_dwc_simple.xsd b/docs/xml/tdwg_dwc_simple.xsd
index 2e63f1a..dcc7b64 100644
--- a/docs/xml/tdwg_dwc_simple.xsd
+++ b/docs/xml/tdwg_dwc_simple.xsd
@@ -1,12 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<xs:schema version="2015-03-19"
+<xs:schema 
+    version="2021-07-15"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="http://rs.tdwg.org/dwc/xsd/simpledarwincore/"
+    xmlns:dc="http://purl.org/dc/elements/1.1/"
     xmlns:dcterms="http://purl.org/dc/terms/"
     xmlns:dwr="http://rs.tdwg.org/dwc/xsd/simpledarwincore/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/">
-    <xs:import namespace="http://rs.tdwg.org/dwc/terms/" schemaLocation="tdwg_dwc_extensions.xsd"/>
-    <xs:import namespace="http://purl.org/dc/terms/" schemaLocation="http://dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"/>
+    <xs:import 
+       namespace="http://rs.tdwg.org/dwc/terms/" 
+       schemaLocation="tdwg_dwc_extensions.xsd"/>
+    <xs:import 
+       namespace="http://purl.org/dc/elements/1.1/" 
+       schemaLocation="http://dublincore.org/schemas/xmls/qdc/dc.xsd"/>
+    <xs:import 
+       namespace="http://purl.org/dc/terms/" 
+       schemaLocation="http://dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"/>
     <xs:annotation>
         <xs:documentation>
             This schema defines Simple Darwin Core records and record sets using the
@@ -18,7 +27,7 @@
         <xs:annotation>
             <xs:documentation>Simple container to encode multiple darwin core records 
                 that have no notion of which class they are. They can therefore represent 
-                a taxon, an observation or just a locality, for example.
+                a taxon, an observation, or just a locality, for example.
             </xs:documentation>
         </xs:annotation>
         <xs:complexType>
@@ -31,9 +40,9 @@
         <xs:complexType>
             <xs:all>
                 <!-- Record-level terms -->
-                <xs:element ref="dcterms:type" minOccurs="0"/>
+                <xs:element ref="dc:type" minOccurs="0"/>
                 <xs:element ref="dcterms:modified" minOccurs="0"/>
-                <xs:element ref="dcterms:language" minOccurs="0"/>
+                <xs:element ref="dc:language" minOccurs="0"/>
                 <xs:element ref="dcterms:license" minOccurs="0"/>
                 <xs:element ref="dcterms:rightsHolder" minOccurs="0"/>
                 <xs:element ref="dcterms:accessRights" minOccurs="0"/>
@@ -55,6 +64,7 @@
                 <xs:element ref="dwc:catalogNumber" minOccurs="0"/>
                 <xs:element ref="dwc:recordNumber" minOccurs="0"/>
                 <xs:element ref="dwc:recordedBy" minOccurs="0"/>
+                <xs:element ref="dwc:recordedByID" minOccurs="0"/>
                 <xs:element ref="dwc:individualCount" minOccurs="0"/>
                 <xs:element ref="dwc:organismQuantity" minOccurs="0"/>
                 <xs:element ref="dwc:organismQuantityType" minOccurs="0"/>
@@ -63,10 +73,14 @@
                 <xs:element ref="dwc:reproductiveCondition" minOccurs="0"/>
                 <xs:element ref="dwc:behavior" minOccurs="0"/>
                 <xs:element ref="dwc:establishmentMeans" minOccurs="0"/>
+                <xs:element ref="dwc:degreeOfEstablishment" minOccurs="0"/>
+                <xs:element ref="dwc:pathway" minOccurs="0"/>
+                <xs:element ref="dwc:georeferenceVerificationStatus" minOccurs="0"/>
                 <xs:element ref="dwc:occurrenceStatus" minOccurs="0"/>
                 <xs:element ref="dwc:preparations" minOccurs="0"/>
                 <xs:element ref="dwc:disposition" minOccurs="0"/>
                 <xs:element ref="dwc:associatedMedia" minOccurs="0"/>
+                <xs:element ref="dwc:associatedOccurrences" minOccurs="0"/>
                 <xs:element ref="dwc:associatedReferences" minOccurs="0"/>
                 <xs:element ref="dwc:associatedSequences" minOccurs="0"/>
                 <xs:element ref="dwc:associatedTaxa" minOccurs="0"/>
@@ -76,7 +90,6 @@
                 <xs:element ref="dwc:organismID" minOccurs="0"/>
                 <xs:element ref="dwc:organismName" minOccurs="0"/>
                 <xs:element ref="dwc:organismScope" minOccurs="0"/>
-                <xs:element ref="dwc:associatedOccurrences" minOccurs="0"/>
                 <xs:element ref="dwc:associatedOrganisms" minOccurs="0"/>
                 <xs:element ref="dwc:previousIdentifications" minOccurs="0"/>
                 <xs:element ref="dwc:organismRemarks" minOccurs="0"/>
@@ -119,6 +132,7 @@
                 <xs:element ref="dwc:minimumElevationInMeters" minOccurs="0"/>
                 <xs:element ref="dwc:maximumElevationInMeters" minOccurs="0"/>
                 <xs:element ref="dwc:verbatimElevation" minOccurs="0"/>
+                <xs:element ref="dwc:verticalDatum" minOccurs="0"/>
                 <xs:element ref="dwc:minimumDepthInMeters" minOccurs="0"/>
                 <xs:element ref="dwc:maximumDepthInMeters" minOccurs="0"/>
                 <xs:element ref="dwc:verbatimDepth" minOccurs="0"/>
@@ -144,7 +158,6 @@
                 <xs:element ref="dwc:georeferencedDate" minOccurs="0"/>
                 <xs:element ref="dwc:georeferenceProtocol" minOccurs="0"/>
                 <xs:element ref="dwc:georeferenceSources" minOccurs="0"/>
-                <xs:element ref="dwc:georeferenceVerificationStatus" minOccurs="0"/>
                 <xs:element ref="dwc:georeferenceRemarks" minOccurs="0"/>
                 <!-- GeologicalContext terms -->
                 <xs:element ref="dwc:geologicalContextID" minOccurs="0"/>
@@ -167,9 +180,11 @@
                 <xs:element ref="dwc:bed" minOccurs="0"/>
                 <!-- Identification terms -->
                 <xs:element ref="dwc:identificationID" minOccurs="0"/>
+                <xs:element ref="dwc:verbatimIdentification" minOccurs="0"/>
                 <xs:element ref="dwc:identificationQualifier" minOccurs="0"/>
                 <xs:element ref="dwc:typeStatus" minOccurs="0"/>
                 <xs:element ref="dwc:identifiedBy" minOccurs="0"/>
+                <xs:element ref="dwc:identifiedByID" minOccurs="0"/>
                 <xs:element ref="dwc:dateIdentified" minOccurs="0"/>
                 <xs:element ref="dwc:identificationReferences" minOccurs="0"/>
                 <xs:element ref="dwc:identificationVerificationStatus" minOccurs="0"/>
@@ -196,10 +211,14 @@
                 <xs:element ref="dwc:class" minOccurs="0"/>
                 <xs:element ref="dwc:order" minOccurs="0"/>
                 <xs:element ref="dwc:family" minOccurs="0"/>
+                <xs:element ref="dwc:subfamily" minOccurs="0"/>
                 <xs:element ref="dwc:genus" minOccurs="0"/>
+                <xs:element ref="dwc:genericName" minOccurs="0"/>
                 <xs:element ref="dwc:subgenus" minOccurs="0"/>
+                <xs:element ref="dwc:infragenericEpithet" minOccurs="0"/>
                 <xs:element ref="dwc:specificEpithet" minOccurs="0"/>
                 <xs:element ref="dwc:infraspecificEpithet" minOccurs="0"/>
+                <xs:element ref="dwc:cultivarEpithet" minOccurs="0"/>
                 <xs:element ref="dwc:taxonRank" minOccurs="0"/>
                 <xs:element ref="dwc:verbatimTaxonRank" minOccurs="0"/>
                 <xs:element ref="dwc:scientificNameAuthorship" minOccurs="0"/>
diff --git a/docs/xml/tdwg_dwcterms.xsd b/docs/xml/tdwg_dwcterms.xsd
index 809319d..ce7ba12 100644
--- a/docs/xml/tdwg_dwcterms.xsd
+++ b/docs/xml/tdwg_dwcterms.xsd
@@ -1,39 +1,56 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <xs:schema 
-    version="2015-03-19"
+    version="2021-07-15"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="http://rs.tdwg.org/dwc/terms/"
+    xmlns:dc="http://purl.org/dc/elements/1.1/"
     xmlns:dcterms="http://purl.org/dc/terms/"
-    xmlns:dcelem="http://purl.org/dc/elements/1.1/"
+    xmlns:chrono="http://rs.tdwg.org/chrono/terms/"
     xmlns:dwc="http://rs.tdwg.org/dwc/terms/">
     <xs:annotation>
         <xs:documentation xml:lang="en">
             The Generic Darwin Core schema defining all property terms as global elements.
             
-            Domain classes are not defined here, but in a separate schema (tdwg_dwcclasses.xsd) with the same namespace.            
-            There are two ways in which references to domains can be defined:
-            a) through an abstract base term anyXXXTerm, which is derived from the type dwc:anyPropery and which all properties
-               for that domain use as their substitution group. If you refer to dwc:anyXXXTerm in your schema, you will be able 
-               to reference any of the terms, but it will be impossible to create a sequence of all terms occurring only once. 
-            b) through a group of elements called XXXTerms, which reference properties exactly once as a sequence. 
-               This group can be used to refer to all the domain properties only once. In order to make a property required, you 
-               must create your own group referring to the individual dwc terms. 
-               If you want to specify every term once at most and in any order, you will also have to refer to the individual dwc 
-               term yourself - a limitation of the xs:all model.
+            Domain classes are not defined here, but in a separate schema 
+            (tdwg_dwc_classes.xsd) with the same namespace. There are two ways in which 
+            references to domains can be defined:
+            a) through an abstract base term anyXXXTerm, which is derived from the type 
+               dwc:anyPropery and which all properties for that domain use as their 
+               substitution group. If you refer to dwc:anyXXXTerm in your schema, you 
+               will be able to reference any of the terms, but it will be impossible to 
+               create a sequence of all terms occurring only once. 
+            b) through a group of elements called XXXTerms, which reference properties 
+               exactly once as a sequence. This group can be used to refer to all the 
+               domain properties only once each. In order to make a property required, 
+               you must create your own group referring to the individual dwc terms. If 
+               you want to specify every term once at most and in any order, you will 
+               also have to refer to the individual dwc term yourself - a limitation of 
+               the xs:all model.
         </xs:documentation>
     </xs:annotation>
-    <!-- tdwg_basetypes.xsd defines custom data types such as dateTimeISO to allow dates or the forms YYYY and YYYY-MM. -->
+
+    <!-- tdwg_basetypes.xsd defines custom data type restrictions such as dateTimeISO,
+       which allows dates of the forms YYYY and YYYY-MM. -->
     <xs:include schemaLocation="tdwg_basetypes.xsd"/>
-    <xs:import namespace="http://purl.org/dc/terms/" schemaLocation="http://dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"/>
-    <xs:import namespace="http://purl.org/dc/elements/1.1/" schemaLocation="http://dublincore.org/schemas/xmls/qdc/dc.xsd"/>
-    <xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/03/xml.xsd"/>
+    <xs:import 
+       namespace="http://purl.org/dc/terms/" 
+       schemaLocation="http://dublincore.org/schemas/xmls/qdc/2008/02/11/dcterms.xsd"/>
+    <xs:import 
+       namespace="http://purl.org/dc/elements/1.1/" 
+       schemaLocation="http://dublincore.org/schemas/xmls/qdc/dc.xsd"/>
+    <xs:import 
+       namespace="http://www.w3.org/XML/1998/namespace" 
+       schemaLocation="http://www.w3.org/2001/03/xml.xsd"/>
+
     <!-- ANY DWC TERM -->
     <xs:element name="any" abstract="true"/>
+
     <!-- ANY DWC IDENTIFIER -->
     <xs:element name="anyIdentifier" abstract="true" substitutionGroup="dwc:any"/>
     <xs:group name="IdentifierTerms">
         <xs:annotation>
-            <xs:documentation>Group of all Darwin Core identifier terms as a convenience to construct other schemas</xs:documentation>
+            <xs:documentation>Group of all Darwin Core class identifier terms as a 
+               convenience to construct other schemas</xs:documentation>
         </xs:annotation>
         <xs:sequence>
             <xs:element ref="dwc:occurrenceID" minOccurs="0"/>
@@ -44,15 +61,19 @@
             <xs:element ref="dwc:geologicalContextID" minOccurs="0"/>
             <xs:element ref="dwc:identificationID" minOccurs="0"/>
             <xs:element ref="dwc:taxonID" minOccurs="0"/>
-            <xs:element ref="dwc:resourceRelationshipID" minOccurs="0"/>
             <xs:element ref="dwc:measurementID" minOccurs="0"/>
+            <xs:element ref="dwc:resourceRelationshipID" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeID" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- ANY DWC PROPERTY TERM -->
     <xs:element name="anyProperty" abstract="true" substitutionGroup="dwc:any"/>
     <!-- type="dwc:simpleProperty"  -->
+
     <!-- ANY DWC CLASS TERM -->
     <xs:element name="anyClass" abstract="true" substitutionGroup="dwc:any"/>
+
     <!-- 
         All TERMS listed BY domain
         Every domain has its own substitutionGroup
@@ -60,7 +81,8 @@
     <!-- RECORD-LEVEL domainless terms -->
     <xs:element name="anyRecordLevelTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <!-- domain properties -->
-    <!-- the Dublin Core terms applicable for Darwin Core are defined in the dublin_core.xsd and use this substitution group -->
+    <!-- the Dublin Core terms applicable for Darwin Core are defined in the 
+      Dublin Core schemas and use this substitution group -->
     <xs:element name="institutionID" substitutionGroup="dwc:anyRecordLevelTerm" type="xs:string"/>
     <xs:element name="collectionID" substitutionGroup="dwc:anyRecordLevelTerm" type="xs:string"/>
     <xs:element name="datasetID" substitutionGroup="dwc:anyRecordLevelTerm" type="xs:string"/>
@@ -74,9 +96,9 @@
     <xs:element name="dynamicProperties" substitutionGroup="dwc:anyRecordLevelTerm" type="xs:string"/>
     <xs:group name="RecordLevelTerms">
         <xs:sequence>
-            <xs:element ref="dcterms:type" minOccurs="0"/>
+            <xs:element ref="dc:type" minOccurs="0"/>
             <xs:element ref="dcterms:modified" minOccurs="0"/>
-            <xs:element ref="dcterms:language" minOccurs="0"/>
+            <xs:element ref="dc:language" minOccurs="0"/>
             <xs:element ref="dcterms:license" minOccurs="0"/>
             <xs:element ref="dcterms:rightsHolder" minOccurs="0"/>
             <xs:element ref="dcterms:accessRights" minOccurs="0"/>
@@ -95,6 +117,7 @@
             <xs:element ref="dwc:dynamicProperties" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- OCCURRENCE domain -->
     <xs:element name="anyOccurrenceTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="occurrenceID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -102,6 +125,7 @@
     <xs:element name="catalogNumber" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="recordNumber" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="recordedBy" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
+    <xs:element name="recordedByID" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="individualCount" type="xs:positiveInteger" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="organismQuantity" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="organismQuantityType" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
@@ -110,11 +134,15 @@
     <xs:element name="reproductiveCondition" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="behavior" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="establishmentMeans" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
+    <xs:element name="degreeOfEstablishmentMeans" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
+    <xs:element name="pathway" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
+    <xs:element name="georeferenceVerificationStatus" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="occurrenceStatus" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="preparations" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="disposition" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="associatedMedia" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="associatedReferences" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
+    <xs:element name="associatedOccurrences" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="associatedSequences" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="associatedTaxa" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
     <xs:element name="otherCatalogNumbers" type="xs:string" substitutionGroup="dwc:anyOccurrenceTerm"/>
@@ -124,6 +152,7 @@
             <xs:element ref="dwc:catalogNumber" minOccurs="0"/>
             <xs:element ref="dwc:recordNumber" minOccurs="0"/>
             <xs:element ref="dwc:recordedBy" minOccurs="0"/>
+            <xs:element ref="dwc:recordedByID" minOccurs="0"/>
             <xs:element ref="dwc:individualCount" minOccurs="0"/>
             <xs:element ref="dwc:organismQuantity" minOccurs="0"/>
             <xs:element ref="dwc:organismQuantityType" minOccurs="0"/>
@@ -132,24 +161,28 @@
             <xs:element ref="dwc:reproductiveCondition" minOccurs="0"/>
             <xs:element ref="dwc:behavior" minOccurs="0"/>
             <xs:element ref="dwc:establishmentMeans" minOccurs="0"/>
+            <xs:element ref="dwc:degreeOfEstablishmentMeans" minOccurs="0"/>
+            <xs:element ref="dwc:pathway" minOccurs="0"/>
+            <xs:element ref="dwc:georeferenceVerificationStatus" minOccurs="0"/>
             <xs:element ref="dwc:occurrenceStatus" minOccurs="0"/>
             <xs:element ref="dwc:preparations" minOccurs="0"/>
             <xs:element ref="dwc:disposition" minOccurs="0"/>
             <xs:element ref="dwc:associatedMedia" minOccurs="0"/>
             <xs:element ref="dwc:associatedReferences" minOccurs="0"/>
+            <xs:element ref="dwc:associatedOccurrences" minOccurs="0"/>
             <xs:element ref="dwc:associatedSequences" minOccurs="0"/>
             <xs:element ref="dwc:associatedTaxa" minOccurs="0"/>
             <xs:element ref="dwc:otherCatalogNumbers" minOccurs="0"/>
             <xs:element ref="dwc:occurrenceRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- ORGANISM domain -->
     <xs:element name="anyOrganismTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="organismID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
     <!-- domain properties -->
     <xs:element name="organismName" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
     <xs:element name="organismScope" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
-    <xs:element name="associatedOccurrences" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
     <xs:element name="associatedOrganisms" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
     <xs:element name="previousIdentifications" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
     <xs:element name="organismRemarks" type="xs:string" substitutionGroup="dwc:anyOrganismTerm"/>
@@ -157,16 +190,17 @@
         <xs:sequence>
             <xs:element ref="dwc:organismName" minOccurs="0"/>
             <xs:element ref="dwc:organismScope" minOccurs="0"/>
-            <xs:element ref="dwc:associatedOccurrences" minOccurs="0"/>
             <xs:element ref="dwc:associatedOrganisms" minOccurs="0"/>
             <xs:element ref="dwc:previousIdentifications" minOccurs="0"/>
             <xs:element ref="dwc:organismRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- MaterialSample domain -->
     <xs:element name="anyMaterialSampleTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="materialSampleID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
     <!-- domain properties -->
+
     <!-- EVENT domain -->
     <xs:element name="anyEventTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="eventID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -183,9 +217,9 @@
     <xs:element name="habitat" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="fieldNumber" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="samplingProtocol" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
-    <xs:element name="samplingEffort" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="sampleSizeValue" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="sampleSizeUnit" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
+    <xs:element name="samplingEffort" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="fieldNotes" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:element name="eventRemarks" type="xs:string" substitutionGroup="dwc:anyEventTerm"/>
     <xs:group name="EventTerms">
@@ -202,13 +236,14 @@
             <xs:element ref="dwc:habitat" minOccurs="0"/>
             <xs:element ref="dwc:fieldNumber" minOccurs="0"/>
             <xs:element ref="dwc:samplingProtocol" minOccurs="0"/>
-            <xs:element ref="dwc:samplingEffort" minOccurs="0"/>
             <xs:element ref="dwc:sampleSizeValue" minOccurs="0"/>
             <xs:element ref="dwc:sampleSizeUnit" minOccurs="0"/>
+            <xs:element ref="dwc:samplingEffort" minOccurs="0"/>
             <xs:element ref="dwc:fieldNotes" minOccurs="0"/>
             <xs:element ref="dwc:eventRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- dcterms:LOCATION domain -->
     <xs:element name="anyLocationTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="locationID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -229,6 +264,7 @@
     <xs:element name="minimumElevationInMeters" type="xs:double" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="maximumElevationInMeters" type="xs:double" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="verbatimElevation" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
+    <xs:element name="verticalDatum" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="minimumDepthInMeters" type="xs:double" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="maximumDepthInMeters" type="xs:double" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="verbatimDepth" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
@@ -254,7 +290,6 @@
     <xs:element name="georeferencedDate" type="dwc:dateTimeISO" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="georeferenceProtocol" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="georeferenceSources" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
-    <xs:element name="georeferenceVerificationStatus" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:element name="georeferenceRemarks" type="xs:string" substitutionGroup="dwc:anyLocationTerm"/>
     <xs:group name="LocationTerms">
         <xs:sequence>
@@ -274,6 +309,7 @@
             <xs:element ref="dwc:minimumElevationInMeters" minOccurs="0"/>
             <xs:element ref="dwc:maximumElevationInMeters" minOccurs="0"/>
             <xs:element ref="dwc:verbatimElevation" minOccurs="0"/>
+            <xs:element ref="dwc:verticalDatum" minOccurs="0"/>
             <xs:element ref="dwc:minimumDepthInMeters" minOccurs="0"/>
             <xs:element ref="dwc:maximumDepthInMeters" minOccurs="0"/>
             <xs:element ref="dwc:verbatimDepth" minOccurs="0"/>
@@ -298,10 +334,10 @@
             <xs:element ref="dwc:georeferencedDate" minOccurs="0"/>
             <xs:element ref="dwc:georeferenceProtocol" minOccurs="0"/>
             <xs:element ref="dwc:georeferenceSources" minOccurs="0"/>
-            <xs:element ref="dwc:georeferenceVerificationStatus" minOccurs="0"/>
             <xs:element ref="dwc:georeferenceRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- GEOLOGICALCONTEXT domain -->
     <xs:element name="anyGeologicalContextTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="geologicalContextID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -344,28 +380,34 @@
             <xs:element ref="dwc:bed" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- IDENTIFICATION domain -->
     <xs:element name="anyIdentificationTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="identificationID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
     <!-- domain properties -->
+    <xs:element name="verbatimIdentification" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="identificationQualifier" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="typeStatus" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="identifiedBy" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
+    <xs:element name="identifiedByID" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="dateIdentified" type="dwc:dateTimeISO" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="identificationReferences" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="identificationVerificationStatus" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:element name="identificationRemarks" type="xs:string" substitutionGroup="dwc:anyIdentificationTerm"/>
     <xs:group name="IdentificationTerms">
         <xs:sequence>
+            <xs:element ref="dwc:verbatimIdentification" minOccurs="0"/>
             <xs:element ref="dwc:identificationQualifier" minOccurs="0"/>
             <xs:element ref="dwc:typeStatus" minOccurs="0"/>
             <xs:element ref="dwc:identifiedBy" minOccurs="0"/>
+            <xs:element ref="dwc:identifiedByID" minOccurs="0"/>
             <xs:element ref="dwc:dateIdentified" minOccurs="0"/>
             <xs:element ref="dwc:identificationReferences" minOccurs="0"/>
             <xs:element ref="dwc:identificationVerificationStatus" minOccurs="0"/>
             <xs:element ref="dwc:identificationRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- TAXON domain -->
     <xs:element name="anyTaxonTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="taxonID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -390,10 +432,14 @@
     <xs:element name="class" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="order" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="family" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
+    <xs:element name="subfamily" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="genus" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
+    <xs:element name="genericName" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="subgenus" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
+    <xs:element name="infragenericEpithet" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="specificEpithet" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="infraspecificEpithet" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
+    <xs:element name="cultivarEpithet" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="taxonRank" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="verbatimTaxonRank" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
     <xs:element name="scientificNameAuthorship" type="xs:string" substitutionGroup="dwc:anyTaxonTerm"/>
@@ -424,10 +470,14 @@
             <xs:element ref="dwc:class" minOccurs="0"/>
             <xs:element ref="dwc:order" minOccurs="0"/>
             <xs:element ref="dwc:family" minOccurs="0"/>
+            <xs:element ref="dwc:subfamily" minOccurs="0"/>
             <xs:element ref="dwc:genus" minOccurs="0"/>
+            <xs:element ref="dwc:genericName" minOccurs="0"/>
             <xs:element ref="dwc:subgenus" minOccurs="0"/>
+            <xs:element ref="dwc:infragenericEpithet" minOccurs="0"/>
             <xs:element ref="dwc:specificEpithet" minOccurs="0"/>
             <xs:element ref="dwc:infraspecificEpithet" minOccurs="0"/>
+            <xs:element ref="dwc:cultivarEpithet" minOccurs="0"/>
             <xs:element ref="dwc:taxonRank" minOccurs="0"/>
             <xs:element ref="dwc:verbatimTaxonRank" minOccurs="0"/>
             <xs:element ref="dwc:scientificNameAuthorship" minOccurs="0"/>
@@ -438,6 +488,7 @@
             <xs:element ref="dwc:taxonRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- MEASUREMENTORFACT domain -->
     <xs:element name="anyMeasurementTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="measurementID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
@@ -462,11 +513,13 @@
             <xs:element ref="dwc:measurementRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
     <!-- RESOURCERELATIONSHIP domain -->
     <xs:element name="anyResourceRelationshipTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
     <xs:element name="resourceRelationshipID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
     <!-- domain properties -->
     <xs:element name="resourceID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyResourceRelationshipTerm"/>
+    <xs:element name="relationshipOfResourceID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyResourceRelationshipTerm"/>
     <xs:element name="relatedResourceID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyResourceRelationshipTerm"/>
     <xs:element name="relationshipOfResource" type="xs:string" substitutionGroup="dwc:anyResourceRelationshipTerm"/>
     <xs:element name="relationshipAccordingTo" type="xs:string" substitutionGroup="dwc:anyResourceRelationshipTerm"/>
@@ -475,6 +528,7 @@
     <xs:group name="ResourceRelationshipTerms">
         <xs:sequence>
             <xs:element ref="dwc:resourceID" minOccurs="0"/>
+            <xs:element ref="dwc:relationshipOfResourceID" minOccurs="0"/>
             <xs:element ref="dwc:relatedResourceID" minOccurs="0"/>
             <xs:element ref="dwc:relationshipOfResource" minOccurs="0"/>
             <xs:element ref="dwc:relationshipAccordingTo" minOccurs="0"/>
@@ -482,4 +536,47 @@
             <xs:element ref="dwc:relationshipRemarks" minOccurs="0"/>
         </xs:sequence>
     </xs:group>
+
+    <!-- CHRONOMETRICAGE domain -->
+    <xs:element name="anyChronometricAgeTerm" abstract="true" substitutionGroup="dwc:anyProperty"/>
+    <xs:element name="chronometriAgeID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyIdentifier"/>
+    <!-- domain properties -->
+    <xs:element name="verbatimChronometricAge" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeProtocol" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="uncalibratedChronometricAge" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeConversionProtocol" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="earliestChronometricAge" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="earliestChronometricAgeReferenceSystem" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="latestChronometricAge" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="latestChronometricAgeReferenceSystem" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeUncertaintyInYears" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeUncertaintyMethod" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="materialDated" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="materialDatedID" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="materialDatedRelationship" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeDeterminedBy" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeDeterminedDate" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeReferences" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:element name="chronometricAgeRemarks" type="dwc:nonEmptyString" substitutionGroup="dwc:anyChronometricAgeTerm"/>
+    <xs:group name="ChronometricAgeTerms">
+        <xs:sequence>
+            <xs:element ref="chrono:verbatimChronometricAge" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeProtocol" minOccurs="0"/>
+            <xs:element ref="chrono:uncalibratedChronometricAge" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeConversionProtocol" minOccurs="0"/>
+            <xs:element ref="chrono:earliestChronometricAge" minOccurs="0"/>
+            <xs:element ref="chrono:earliestChronometricAgeReferenceSystem" minOccurs="0"/>
+            <xs:element ref="chrono:latestChronometricAge" minOccurs="0"/>
+            <xs:element ref="chrono:latestChronometricAgeReferenceSystem" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeUncertaintyInYears" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeUncertaintyMethod" minOccurs="0"/>
+            <xs:element ref="chrono:materialDated" minOccurs="0"/>
+            <xs:element ref="chrono:materialDatedID" minOccurs="0"/>
+            <xs:element ref="chrono:materialDatedRelationship" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeDeterminedBy" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeDeterminedDate" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeReferences" minOccurs="0"/>
+            <xs:element ref="chrono:chronometricAgeRemarks" minOccurs="0"/>
+        </xs:sequence>
+    </xs:group>
 </xs:schema>