introduces dcr:datacat and dcr:ValueDatacat attributes that may be used to align XML elements or attributes with the appropriate Data Categories (DCs) defined by the ISO 12620:2009 standard and stored in the Web repository called ISOCat at http://www.isocat.org/. contains a PID (persistent identifier) that aligns the given element with the appropriate Data Category (or categories) in ISOcat. contains a PID (persistent identifier) that aligns the content of the given element or the value of the given attribute with the appropriate simple Data Category (or categories) in ISOcat.

In this example dcr:datcat relates the feature name to the data category "partOfSpeech" and dcr:valueDatcat the feature value to the data category "commonNoun". Both these data categories reside in the ISOcat DCR at www.isocat.org, which is the DCR used by ISO TC37 and hosted by its registration authority, the MPI for Psycholinguistics in Nijmegen.

ISO 12620:2009 is a standard describing the data model and procedures for a Data Category Registry (DCR). Data categories are defined as elementary descriptors in a linguistic structure. In the DCR data model each data category gets assigned a unique Peristent IDentifier (PID), i.e., an URI. Linguistic resources or preferably their schemas that make use of data categories from a DCR should refer to them using this PID. For XML-based resources, like TEI documents, ISO 12620:2009 normative Annex A gives a small Data Category Reference XML vocabulary (also available online at http://www.isocat.org/12620/), which provides two attributes, dcr:datcat and dcr:valueDatcat.