Proof structure confusing

I’m working on Android code to display/perform proofs. I notice that in the User structure, there’s (omitting quotation marks)

proofs_summary : {
by_proof_type : { twitter : [ {}, {}], github... }
by_presentation_group : { twitter : [ {}, {} ], github... }
all: [ {}, {}, ]
}

What’s the thinking behind this structure, and what guidance do you have for client authors? My instinct is to just run through proofs_summary/all/\* - is the order in there significant?

Start by reviewing the User structure and the proofs_summary fields named in the issue, especially by_proof_type, by_presentation_group, and all. Determine the intended rationale, whether proofs_summary/all order is significant, and what client authors should rely on; done means documenting that guidance clearly for Android and other clients.

Written by the indexing model from the issue text.