Notes on Controlled Vocabularies

2014-10-23 Joachim Wackerow (meeting  with Knut Wenzig, Justin Lynch, Sanda Ionescu)

Current Approach of DDI Controlled Vocabularies

• Value of the Code

• Descriptive Term of the Code

• Definition of the Code

Hierarchy is expressed by a separator (“.”) in the code. Leftmost string is the highest level.

Both, term and definition can be multi-lingual.

The American English expression is the canonical version.

Current CVs in DDI 3

• External controlled vocabularies

• CodeList/CategoryScheme with nested codes for expressing hierarchy

• Enumerated lists in XML Schema

Multiple Purposes

• Code lists

• Classification

• Controlled vocabularies

Requirements

• General

  • Ideally only one type of structure for multiple purposes

  • Usage of existing structures preferred if possible (like SKOS in the Semantic Web)

  • Same structure for internal representation in the model/specification and external representation. Reasoning: easy processing, same software solution, only different reference.

  • Validation of structure, keys, and possibly values

    • What should be validated: keys, values, relationship, dependency, requirement, …

    • XML Schema: what should be validated by XML parser, what in a secondary-level validation

• Simple approach

  • Hierarchy

  • Multi-lingual text for term and definition

  • As simple as possible, easy to process

• Complex

  • Requirement of items

  • Relationship of items

    • use case thesaurus

    • CV for keys, CV for values of key/value pair

Conclusion

Current sense: Two different approaches required: a simple CV structure similar to the approach for the current DDI Controlled Vocabularies and a more complex approach for additional requirements like validation and defining requirements.

Ideally the complex approach could make use of the simple approach.