I'm not sure what the status of this WG is, but I've been doing some work to advance a data type registry (I call it a vocabulary and information model registry...) for some EarthCube Projects. There's a post at https://rd-alliance.org/group/data-type-registries-wg/post/re-data-type-..., and the docs are online at
https://github.com/usgin/usginspecs/raw/gh-pages/DataTypeModelDraft.pdf > Draft UML model for vocabulary and information registry</a> The scope of this model is the formal representation of information objects that are the basic units of data representation in computer information systems. The model specifies the concept of a DataObject ('type', 'entity', 'object', etc.) that has a collection of attributes, with domains and cardinalities for those attributes, constituting the representation of instances of that type/entity. The model distinguishes the conceptual level definition of these objects and attributes from the implementation of those concepts with a particular representation. Description and documentation of the conceptual level (ObjectClass and Properties) is important for interfaces through which domain practitioners interact with data. Description and documentation of the implementation level (DataObject and DataElements) is important for software systems that automate operations on the data. Representation of the conceptual objects might be implemented as JSON objects, XML elements, rows in a relation, RDF graphs etc.
If any one is interested in looking at the Enterprise Architect document, please contact me.