BIDS-Prov Json validator

[cmaumet]

Suggestion by @yarikoptic

schema for JSON records would be defined within BIDS schema (here is current for GeneratedBy) to be validatable by stock bids-validator

Yes, this is something I hope we can aim for in the current version of the BIDS-Prov standard. Note that amongst all the possible way to serialize JSON-LD graphs, the spec focused on two specific ways see "BIDS-Prov JSON-LD file" and "Alternative representation for file-level provenance JSON-LD". -->