Work on a JSON implementation of an enriched data type model

Testing and experimentation with data type representations implementing the USGIN proposed model that extends the WG v. 1. The model is described in an online document.

Data type descriptions were compiled for testing from some of the USGIN content models. The various data type representation components were assembled in spreadsheets to deduplicate properties from the various NGDS content models.  The first implementation tested was based on RDF, but the workflow for getting from the compilations to the encoding was found to be cumbersome based on the skill set available in the team. Experimentation with the Cordra data type registry described at the RDA Plenary in Tokyo indicates that a simpler workflow should be possible using that. We have deployed a Cordra test bed, and implemented the Data type registry model as a JSON schema. The attached JSON schema (AttributeSchema-, DataObjectSchema-, SKOSConceptSchema- ...USGINv.3-Cordra.JSON) are from the Cordra tests and include some cordra specific keys; the schema implement a simplified version of the full USGIN Data Type model as a starting point. An example instance document is also attached (JSONDataTypeTest.JSON).  A complete JSON schema is also attached (DataTypeJSON0.1.json).  All work is accessible in the USGIN/digital-crustLDR github.   All the JSON files are in a zip archive.