DataHarmonizer ontology data saving format option

[ddooley]

We will be adding a format in which any categorical value, and any column header and unit, will be saveable as ontology ids rather than textual labels in tsv and other formats. One would supply the ids as right hand column URLs in the DataHarmonizer google sheet specification for a given format; these are then included in the data.js configuration file.

This stops short of storing data as RDF structured ontology triple store, but that knowledge graph focused output requires standardization of measurable datum templates, which is a second level of sophistication and requires more consensus work within OBOFoundry.