Some fields should suggest a subset of a given ontology

From @sveinugu:

Since e.g. not all terms in the OBI ontology describe experiment assays, it might be an idea to specify that for the “assay_type” field, all terms should have the “assay” concept as an ancestor: (https://bioportal.bioontology.org/ontologies/OBI?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FOBI_0000070)

And similarly for other fields specifying terms. We did this in the FAIRtracks model, e.g.[ https://github.com/fairtracks/fairtracks_standard/blob/master/docs/fairtracks_experiment-properties-experimental-technique.md#term_id](https://github.com/fairtracks/fairtracks_standard/blob/master/docs/fairtracks_experiment-properties-experimental-technique.md#term_id) (Here we used the more generic concept “planned process” as the ancestor for a more generic field “experimental technique”:[ https://bioportal.bioontology.org/ontologies/OBI?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FOBI_0000011](https://bioportal.bioontology.org/ontologies/OBI?p=classes&conceptid=http%3A%2F%2Fpurl.obolibrary.org%2Fobo%2FOBI_0000011))

Start by reviewing the issue's OBI BioPortal links and the referenced FAIRtracks experimental-technique documentation. Identify which metadata fields specify ontology terms and determine the expected ancestor constraints; the work is done when the applicable fields and their ontology subsets are explicitly defined in the standard.

Written by the indexing model from the issue text.