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Document Status
: Current Standard
## 1. Introduction
## 1 Introduction
Each method of encoding information using Darwin Core [[DWC](http://rs.tdwg.org/dwc/index.htm)] has a guide explaining how to use the Darwin Core terms in that situation. This is the guide for encoding biodiversity data using the Resource Description Framework [[RDF](http://www.w3.org/TR/rdf11-concepts/)].
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To facilitate achieving the clarity that RDF makes possible, this guide provides different approaches for each of these four situations in which string values are provided. In the first three situations, the existing term from Darwin Core namespace _dwc:_ can be used with a literal value to expose the string value as it currently exists in a text-based database. This allows for the rapid deployment of RDF described in [Section 1.4.3](./index.htm#1.4.3_Use_of_Darwin_Core_terms_in_RDF) and is all that is required in the first situation ([Section 1.5.1](./index.htm#1.5.1_Situations_where_a_string_is_the_standard_means_for_encodi)). In the second situation ([Section 1.5.2](./index.htm#1.5.2_Situations_where_a_string_value_serves_as_a_proxy_for_a_no)), analogues of the existing _dwc:_ terms have been created in the _dwciri:_ namespace which are intended to be used with IRI-references rather than names. In the third situation ([Section 1.5.3](./index.htm#1.5.3_Situations_where_a_string_value_serves_as_a_keyword_to_ena)), new _dwciri:_ terms have been created to relate subject resources to IRI-identified object resources which form part of a hierarchy. If such a hierarchy already exists, the need is eliminated for separate terms (“convenience terms”) which relate the subject resource to all parts of the hierarchy, although those terms can still be used if they are convenient for facilitating string searches. The last situation ([Section 1.5.4](./index.htm#1.5.4_Situations_where_a_string_value_serves_as_an_identifier)) is more complex and a significant part of the implementation guide is devoted to the ways in which RDF should be structured to handle various kinds of identifiers.
## 2. Implementation Guide
## 2 Implementation Guide
### 2.1 Definitions
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          dwc:measurementRemarks "Accuracy from significant digits."@en].
```
## 3. Term reference
## 3 Term reference
This section organizes terms from Darwin Core and other key vocabularies according to their use in RDF. If the use of a term has additional restrictions or implications (e.g., domain and range assertions), they are noted. Recommended formats and values are given when appropriate.
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dwc:previousIdentifications | There is no consensus object property for associating identifications with resources of other classes. From whatever scheme you have chosen to provide object properties, use same object property as used for the most recent identification but provide an earlier dwc:dateIdentified value.
dwc:organismScope | Use rdf:type with a non-literal object. See the comment at http://rs.tdwg.org/dwc/terms/organismScope.
## 4. References
## 4 References
Resource | Link | Description
--- | --- | ---

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Document Status
: Current Standard
## 1. Introduction
## 1 Introduction
**Audience**: This document is targeted toward those who want to share biodiversity information using the simplest methods and structure: Simple Darwin Core. It explains the uses and limitations of this structure and how to expand upon it.
## 2. What is Simple Darwin Core?
## 2 What is Simple Darwin Core?
Simple Darwin Core is a predefined subset of the terms that have common use across a wide variety of biodiversity applications. The terms used in Simple Darwin Core are those that are found at the cross-section of taxonomic names, places, and events that document biological occurrences on the planet. The two driving principles are simplicity and flexibility.
## 3. What makes it simple?
## 3 What makes it simple?
Simple Darwin Core is simple in that it assumes (and allows) no structure beyond the concept of rows and columns, which might be thought of as attributes and their values, or fields and records. The words field and record will be used throughout the rest of the document to refer to the two dimensions of the Simple Darwin Core structure. Think of the term names as the field names. In other words, a Simple Darwin Core record could be captured in a spreadsheet or in a single database table.
## 4. What makes it flexible?
## 4 What makes it flexible?
Simple Darwin Core has minimal restrictions on which fields are required (none). You might argue that there should be more required fields, that there isn't anything useful you can do without them. That is partially true. A record with no fields in it wouldn't be very interesting, but there is a difference between requiring that there be a field in a record and requiring that a particular field be in all records. By having no required field restriction, Simple Darwin Core can be used to share any meaningful combination of fields - for example, to share "just names", or "just places", or observations of individuals detected in the wild at a given place and time following a method (an occurrence). This flexibility promotes the reuse of the terms and sharing mechanisms for a wide variety of services.
## 5. Are there any rules?
## 5 Are there any rules?
There are just a few general guiding principles on how to make the best use of Simple Darwin Core:
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There is a difference between having data in a field and requiring that field to have a value from among a legal set of values. Darwin Core is simple in that it has minimal restrictions on the contents of fields. The term comments give recommendations about the use of controlled vocabularies and how to structure content wherever appropriate. Data contributors are encouraged to follow these recommendations as well as possible. You might argue that having no restrictions will promote "dirty" data (data of low quality or dubious value). Consider the simple axiom "It's not what you have, but what you do with it that matters." If data restrictions were in place at the fundamental level, then a record having any non-compliant data in any of its fields could not be shared via the standard. Not only would there be a dearth of shared data in that case (or an unused standard), but also there would be no way to use the standard to build shared data cleaning tools to actually improve the situation, nor to use data services to look up alternative representations (language translations, for example) to serve a broader audience. The rest is up to how the records will be used - in other words, it is up to applications to enforce further restrictions if appropriate, and it is up to the stakeholders of those applications to decide what the restrictions will be for the purpose the application is trying to serve.
## 6. How do I use Simple Darwin Core?
## 6 How do I use Simple Darwin Core?
Darwin Core is simple in that data "complying with" Simple Darwin Core can be easily shared in a variety of ways, including, but not limited to, text files and xml documents. Equivalent ways of sharing the same data are described in the sections [Simple Darwin Core as Text](#61-simple-darwin-core-as-text) and [Simple Darwin Core as XML](#62-simple-darwin-core-as-xml).
@ -128,7 +128,7 @@ The [XML guide](../xml/) describes how to construct XML schemas to share data ba
The `SimpleDarwinRecord` acts as a `Class` in implementation, because all of the terms are properties of it. The Simple Darwin Core schema has just one other level of structure, the `SimpleDarwinRecordSet`, which is a grouping of one or more `SimpleDarwinRecords`. The `SimpleDarwinRecordSet` acts as a `Class` to define a data set during implementation.
## 7. Doing more with Simple Darwin Core
## 7 Doing more with Simple Darwin Core
Sooner or later you may want to share more information than Simple Darwin Core seems to allow. For example, you and your colleagues might decide that it would be useful to have a standard way to exchange additional information relevant to questions in Conservation. How would you do it?
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So, if you really need to extend the capabilities of Darwin Core, the best first step is to follow the standards process to add the terms you need. See the [Contributing guide](https://github.com/tdwg/dwc/blob/master/.github/CONTRIBUTING.md) to understand how to suggest a new term.
## 8. Going beyond Simple Darwin Core
## 8 Going beyond Simple Darwin Core
For cases where rich data require rich (non-simple) structure, Simple Darwin Core alone is not suitable. When sharing information via [Fielded Text](http://www.fieldedtext.org/), the solution is to use Simple Darwin Core as a core record with one or more associated extensions for the additional information. See the [Text guide](../text/) for an explanation and examples.

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Document Status
: Current Standard
## 1. Introduction
## 1 Introduction
This document provides guidelines for formatting and sharing [Darwin Core terms](http://rs.tdwg.org/dwc/terms) in _fielded text_ formats, such as one or more comma separated value (CSV) files. Data conforming to the [Simple Darwin Core](../simple/) (CSV format and having the first row include Darwin Core standard term names) can be shared in a single file, while a non-standard text file can be understood using an [XML](http://www.w3.org/XML/) metafile to describe its contents and formatting.
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- The transfer of large numbers of Darwin Core records and related data from one database to another. Typically databases are very efficient at exporting and importing comma separated text files.
- The description of legacy data existing in a fielded text format, such that it might be automatically understood and loaded into another system. It could be that this system would then serve the data in another format such as XML.
## 2. Metafile content
## 2 Metafile content
The [text metafile schema](tdwg_dwc_text.xsd) provides technical details for the structure of a metafile by defining the elements and attributes required to describe the contents and relationships between text files. These elements and attributes, with descriptions and specifications for their use in a metafile, are described in the following table.
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`default` | Specifies value to use if one is not supplied for the field in a given row. If no index is supplied, the default can be used to define a constant for all rows for a field that is not in the data file. | no |
`vocabulary` | A Unified Resource Identifier (URI) for a vocabulary that the source values for this field are based on. The URI ideally should resolve to some machine readable definition like SKOS, RDF or at least some simple text or html file often found for ISO or RFC standards. For example http://rs.gbif.org/vocabulary/gbif/nomenclatural_code.xml, http://www.ietf.org/rfc/rfc3066.txt or http://www.iso.org/iso/list-en1-semic-3.txt. | no |
## 3. Implementation guide
## 3 Implementation guide
### 3.1 Extension example
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</archive>
```
## 4. Database example
## 4 Database example
### 4.1 MySQL

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Document Status
: Current Standard
## 1. Introduction
## 1 Introduction
**Audience**: This document is targeted toward those who wish to use or construct application schemas using Darwin Core terms in XML. It includes explanations of existing schemas such as [Simple Darwin Core](../simple/) and how to build new schemas to meet specific models of information.
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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.
## 2. Implementation guide
## 2 Implementation guide
### 2.1 XML schema