Generalize BIDS common principles as a "data structure standard (DSS)"

[yarikoptic]

Yet another idea from a recent road trip with @effigies which I am trying to put to bytes before it is forgotten.

BIDS itself was built on some original principles in how to organize/name files and what metadata to extract and where to place it. We already have a good number of common principles defined in https://github.com/bids-standard/bids-specification/blob/master/src/common-principles.md but they

• hardcode some specific decisions (sub-*/ folders at top level)
• do not provide a generic guidance for how metadata is "summarized" in {entities}.tsv etc.
• mix generic principles with some "BIDS or neuroimaging specifics" through examples or explicitly listing some specific entities
• some (Inheritance) are still subject to debate

So the idea is potentially to see redefining/extending Common principles as generic rules to produce BIDS itself or any other BIDS-like (#62) standard which would potentially have different entities, metadata fields, file formats, default folder levels from some entities. So pretty much would be a different src/schema to drive it.

Initial suggested codename could be DSS: Data Structure Standard, so BIDS is just a Brain Imaging instance of the DS.

Here is some of the common principles aspects with some of the issues discussed in the scope of BIDS-2.0. I think that if we decide on generalization of common principles so they do not carry any specifics (formats, specific entities etc) in them, and formalize some missing (e.g. specification/decision on what goes into an {entity}-{value}/ folder) ones, it would be great to develop even more generic rules which might later be adopted by other communities, but also might simplify tooling by separating principles from specifics (which we already kinda doing with schema)

• folder/files naming conventions
  • data file(s) + .json
  • Make it possible to specify folders layout to be other than sub-{label}/[ses-{label}/] #54
• composition of datasets
  • sourcedata/, rawdata/, derivatives/
  • Allow composition of a BIDS dataset (dataset level) from smaller (subj or subj/ses) level #59
• inheritance/summarization
  • Replace "inheritance" with "summarization" principle #65