hoisting scheme without hoisting unit roles

[jtauber]

The spec describes hoisting the scheme and docid but only in the case where the unit roles are also hoisted.

What if we want to hoist the scheme (and/or docid) without hoisting unit roles?

For example in this record from the ClearAligner spec:

{
  "meta": {
    "id": "d6820b2b-1a30-4247-a16f-18ed0c89b469",
    "origin": "manual",
    "status": "needsReview",
    "note": [
      {
        "note": "This is how a note is stored.",
        "id": "687280fd-386e-4263-bbab-de0373331086",
        "authorEmail": "name@domain.com"
      }
    ]
  },
  "source": [
    "40001001001"
  ],
  "target": [
    "40001001001",
    "40001001002",
    "40001001003",
    "40001001004"
  ]
}

[jtauber]

A couple of possible solutions:

1. we allow documents to be an object in this case (not just a list), e.g.

[
  {
    "documents": {
      "source": {"scheme": "BCVWP"},
      "target": {"scheme": "BCVWP"}
    },
    "records": [
      ...
    ]
  }
]

2. we allow scheme at the group-level.

[
  {
    "scheme": "BCVWP",
    "records": [
      ...
    ]
  }
]

We could support both. 2 is the most elegant specifically for the ClearAligner case but 1 is more generally useful (and would be necessary for audio where the things being aligned have different schemes).

Note this whole issue doesn't arise if the unit roles are hoisted. The spec already handles that case.

So option 3 would be to leave the spec as-is and require the ClearAligner case to hoist the unit roles. In other words, instead of

"source": [
  "40001001001"
],
"target": [
  "40001001001",
  "40001001002",
  "40001001003",
  "40001001004"
]

just have

"references": [["40001001001"], ["40001001001", "40001001002", "40001001003", "40001001004"]]

with a

"roles": ["source", "target"]

on the group.