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update based on removal of subproperty declarations

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Steve Baskauf 2021-08-05 16:27:48 -05:00
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@ -589,7 +589,7 @@ In the [RDF 1.1 Semantics](http://www.w3.org/TR/rdf11-mt/#literals-and-datatypes
##### 2.4.1.2 Terms intended for use with literal objects (normative)
The definitions of some terms make it clear that they SHOULD be used with literal objects. Darwin Core specifically "imports" several [Dublin Core terms](http://dublincore.org/documents/dcmi-terms/) into its vocabulary for use in describing biodiversity data. In some cases, terms in the `dcterms:` namespace have range declarations of `rdfs:Literal` and are therefore understood to be intended for use with literal objects (strings). In some vocabularies, certain terms are understood to have literal objects because in their definitions they are declared to be `owl:Datatype` properties. In the case of Darwin Core terms in the `dwc:` (`http://rs.tdwg.org/dwc/terms/`) namespace, the normative term definitions in RDF do not include any declarations that indicate whether the terms are intended to be used with literal or IRI reference objects. (Exceptions to this are the various date-related terms, which inherit the range `rdfs:Literal` because they are `rdfs:subPropertyOf` `dcterms:date`.) However, because the `dwc:` terms were originally designed to accommodate text and XML data transfer, their definitions generally specify how term values ought to be expressed as string literals. This guide establishes the convention that terms in the `dwc:` namespace SHOULD be restricted to use with literal objects so that their use in RDF will be consistent with their definitions. As discussed in [Section 1.4.3](#143-use-of-darwin-core-terms-in-rdf-normative) and [Section 2.5](#25-terms-in-the-dwciri-namespace-normative), this guide introduces a separate namespace `http://rs.tdwg.org/dwc/iri/` (abbreviated as `dwciri:`) for additional Darwin Core terms which are intended to have objects that are IRI references.
The definitions of some terms make it clear that they SHOULD be used with literal objects. Darwin Core specifically "imports" several [Dublin Core terms](http://dublincore.org/documents/dcmi-terms/) into its vocabulary for use in describing biodiversity data. In some cases, terms in the `dcterms:` namespace have range declarations of `rdfs:Literal` and are therefore understood to be intended for use with literal objects (strings). In some vocabularies, certain terms are understood to have literal objects because in their definitions they are declared to be `owl:Datatype` properties. In the case of Darwin Core terms in the `dwc:` (`http://rs.tdwg.org/dwc/terms/`) namespace, the normative term definitions in RDF do not include any declarations that indicate whether the terms are intended to be used with literal or IRI reference objects. However, because the `dwc:` terms were originally designed to accommodate text and XML data transfer, their definitions generally specify how term values ought to be expressed as string literals. This guide establishes the convention that terms in the `dwc:` namespace SHOULD be restricted to use with literal objects so that their use in RDF will be consistent with their definitions. As discussed in [Section 1.4.3](#143-use-of-darwin-core-terms-in-rdf-normative) and [Section 2.5](#25-terms-in-the-dwciri-namespace-normative), this guide introduces a separate namespace `http://rs.tdwg.org/dwc/iri/` (abbreviated as `dwciri:`) for additional Darwin Core terms which are intended to have objects that are IRI references.
#### 2.4.2 Non-literal object resources (normative)
@ -897,6 +897,10 @@ would be valid RDF. However, best practices ([Section 2.4.2.1.1](#24211-objects-
#### 2.6.1 Unintended consequences of using Darwin Core ID terms in RDF (non-normative)
**Note added in 2021-07-15 version:**
**When the Darwin Core vocabulary was brought into conformance with the [Standards Documentation Specification](http://rs.tdwg.org/sds/doc/specification/), in order to comply with [Section 4.4.2.2](http://rs.tdwg.org/sds/doc/specification/#44-vocabularies-term-lists-and-terms), all subproperty declarations were removed from the term metadata. Therefore, the effects described in this section are no longer entailed by RDF metadata describing any Darwin Core terms. This explanation has been retained to explain part of the rationale for why ID terms were not recommended for use with RDF in the original specification.**
The previous section showed that using a Darwin Core ID term to indicate the identifier associated with the subject resource is not necessary because there are well-known means in RDF (the `rdf:about` attribute and the `dcterms:identifier` property) for exposing the subject’s identifier. However, as shown below, using a Darwin Core ID term to identify an object resource (as shown in the non-RDF XML Example 21) would actually be problematic. In its normative definition, each Darwin Core ID term is declared to be `rdfs:subPropertyOf` `dcterms:identifier`. In RDF, the purpose of a subproperty declaration is to allow a client with reasoning capability to infer a triple containing a broader (and presumably more well-known) property. In the terminology of Dublin Core, the "ID" term is a [qualifier](https://www.dublincore.org/specifications/dublin-core/usageguide/qualifiers/) which "refines" a basic Dublin Core term and the process of inferring a broader meaning from a more specific term is called a "dumb-down" operation. If a provider attempting to expose the data of Table 3 as RDF used the `dwc:taxonID` term as a property of the identification as shown in the (incorrect) Example 23:
**Example 23:**
@ -1368,7 +1372,7 @@ dcterms:bibliographicCitation | dcterms:BibliographicResource | rdfs:Literal
Darwin Core term | Notes on expressing as RDF
--- | ---
`dwc:eventDate`<br>`dwc:georeferencedDate`<br>`dwc:dateIdentified`<br>`dwc:relationshipEstablishedDate`<br>`dwc:measurementDeterminedDate` | These date terms have range `rdfs:Literal`[^8]. Best practice as specified in the term definition recommends that they SHOULD be formatted according to [ISO 8601-1:2019](https://en.wikipedia.org/wiki/ISO_8601). There is no defined [XML Schema datatype](https://www.w3.org/TR/xmlschema11-2/) that corresponds exactly to ISO 8601-1:2019, therefore the entire set of possible values cannot be specified using an `rdf:datatype` attribute. The [XML Schema dateTime datatype](https://www.w3.org/TR/xmlschema11-2/#dateTime) (`xsd:dateTime`) which is effectively a subset of ISO 8601-1:2019, MAY be used as an `rdf:datatype` attribute. However, `xsd:dateTime` requires the complete series of year, month, day, hour, second (e.g., 002-10-10T12:00:00) and does not permit listing only part of this hierarchy (e.g., only the year) as is allowed in ISO 8601-1:2019.
`dwc:eventDate`<br>`dwc:georeferencedDate`<br>`dwc:dateIdentified`<br>`dwc:relationshipEstablishedDate`<br>`dwc:measurementDeterminedDate` | Best practice as specified in the term definition recommends that they SHOULD be formatted according to [ISO 8601-1:2019](https://en.wikipedia.org/wiki/ISO_8601). There is no defined [XML Schema datatype](https://www.w3.org/TR/xmlschema11-2/) that corresponds exactly to ISO 8601-1:2019, therefore the entire set of possible values cannot be specified using an `rdf:datatype` attribute. The [XML Schema dateTime datatype](https://www.w3.org/TR/xmlschema11-2/#dateTime) (`xsd:dateTime`) which is effectively a subset of ISO 8601-1:2019, MAY be used as an `rdf:datatype` attribute. However, `xsd:dateTime` requires the complete series of year, month, day, hour, second (e.g., 002-10-10T12:00:00) and does not permit listing only part of this hierarchy (e.g., only the year) as is allowed in ISO 8601-1:2019.
`dwc:eventTime` | It is RECOMMENDED that the format described by [ISO 8601-1:2019](https://en.wikipedia.org/wiki/ISO_8601) be used. As with the date terms, there is no [XML Schema datatype](https://www.w3.org/TR/xmlschema11-2/) that includes all of the possible values allowed in ISO 8601-1:2019, so there is no generic `rdf:datatype` attribute that would apply to all possible instances. The [XML Schema dateTime datatype](https://www.w3.org/TR/xmlschema11-2/#dateTime) (`xsd:time`) which is effectively a subset of ISO 8601-1:2019 MAY be used as an `rdf:datatype` attribute although it is limited to values that include hours, minutes, and seconds (e.g., 13:07:56-05:00).
`dwc:individualCount`<br>`dwc:decimalLatitude`<br>`dwc:decimalLongitude`<br>`dwc:coordinatePrecision`<br>`dwc:pointRadiusSpatialFit`<br>`dwc:coordinateUncertaintyInMeters`<br>`dwc:minimumElevationInMeters`<br>`dwc:maximumElevationInMeters`<br>`dwc:minimumDepthInMeters`<br>`dwc:maximumDepthInMeters`<br>`dwc:minimumDistanceAboveSurfaceInMeters`<br>`dwc:maximumDistanceAboveSurfaceInMeters`<br>`dwc:startDayOfYear`<br>`dwc:endDayOfYear`<br>`dwc:year`<br>`dwc:month`<br>`dwc:day`<br>`dwc:footprintSpatialFit`<br>`dwc:measurementAccuracy` | These terms are expected to have literal values that are numeric. Therefore, an `rdf:datatype` attribute describing the form of the number SHOULD be used.
`dwc:occurrenceRemarks`<br>`dwc:eventRemarks`<br>`dwc:locationRemarks`<br>`dwc:georeferenceRemarks`<br>`dwc:identificationRemarks`<br>`dwc:taxonRemarks`<br>`dwc:organismRemarks`<br>`dwc:relationshipRemarks`<br>`dwc:measurementRemarks` | Because these are remarks, they SHOULD have literal values with an `xml:lang` attribute.
@ -1377,8 +1381,6 @@ Darwin Core term | Notes on expressing as RDF
`dwc:basisOfRecord` | MUST be used only with literal value strings consisting of the local name component of Darwin Core class IRIs. Use `rdf:type` to refer to IRIs that describe the type of the resource.
`dwc:dynamicProperties` | Expected to contain JSON as a literal. Communities of practice MAY choose to use other vocabularies or develop their own vocabularies to express this sort of content directly as RDF.
[^8]: No Darwin Core terms defined by Darwin Core (as opposed to those imported from Dublin Core) have domain or range declarations as a part of their definitions. However, the five terms in the `dwc:` namespace listed in the table above are defined to be `rdfs:subPropertyOf` of `dcterms:date`, which has the range `rdfs:Literal`. Under the extensional entailment rule ext4 listed in section 7.3.1 of the [RDF Semantics 2004 W3C Recommendation](http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#RDFSExtRules), these terms can be inferred to have the range `rdfs:Literal`. However, the [RDF 1.1 Semantics W3C Recommendation](http://www.w3.org/TR/rdf11-mt/) does not include these extensional entailment rules. Nevertheless, it is reasonable to expect that date properties will have literal values, with datatype attributes whenever possible.
### 3.5 Darwin Core convenience terms that are expected to be used only with literal values (normative)
See [Section 2.7](#27-darwin-core-convenience-terms-non-normative) for more information on "convenience" terms.