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SimpleCodelistReference.md

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Simplified Codelist Reference

Category Alternate Structures for specific types or type hierarchies
Description

References to codelists are one of the ubiquitous characteristics of the INSPIRE data specifications. They are usually encoded using a ReferenceType, which is derived from an xlink. In the conceptual model, they are represented using property types that point to classes with a <<Codelist>> stereotype.

The main usability issue with ReferenceTypes is that they encode all relevant information in the xlink attributes of the element. In particular, the actual external link is encoded in the xlink:href attribute, while additional informaiton may be encoded in attributes such as xlink:title. An additional issue is that the actual, full codelist URLs are unwieldy to use for styling and filtering in most GIS. It would be much preferable to use the local codelist values. There is a recommendation to encode these using the mentioned xlink:title, but no strict requirement.

This simplified codelist reference takes the property name and uses it to encode the title directly, while all othe properties are modelled as "subproperties":

  • reference
  • reference.href

Both of these properties are mandatory in the SimpleCitation, while extra properties such as arcRole, owns and type are optional..
Original instance in default encoding: 
<ad:Address gml:id="MIG20172_example_Address">
  <!-- ... -->
  <ad:status
    xlink:href="http://inspire.ec.europa.eu/codelist/StatusValue/current"
    xlink:title="current" />
  <!-- ... -->
</ad:Address>
Transformed instance in default encoding: 
<ads:Address gml:id="MIG20172_example_Address">
  <!-- ... -->
  <simple:status>current</ads:status>
  <simple:status.href>http://inspire.ec.europa.eu/codelist/StatusValue/current</ads:status.href>
  <!-- ... -->
</ads:Address>
Model transformation rule:

Parameters:

  • type: The property for which the ReferenceType is to be substituted, e.g. status.

Substitute existing ReferenceType on the type property with this SimpleReference type.
Instance transformation rule:
  • Copy the value of the xlink:title attribute to the property with the name of the type parameter.
  • Copy the value of the xlink:href attribute to the property with the name of the type.href parameter.
Solves usability issues: The transformed data structure can easily be edited, filtered and symbolized in desktop GIS and web GIS software.
Known usability issues: None.
INSPIRE Compliance: Fully compliant.

Notes:

  • None.