I'd like to solicit opinions on this suggestion:

We have been assuming we needed more than just 1d array support, but this is now unclear.

We've pushed back on "top-down" use of XML Schemas, i.e., DFDL must be used bottom up, and transformation into the "logical form you wanted" is not our job. That is, the DFDL Schema's logical organization is constrained (heavily) by the data format.

We could take an exactly analogous position with respect to multi-dimensional or other complex arrays.

The DFDL describes the representation, and the sttructure of the DFDL schema will end up matching the shape of the representation of the array. Transforming that into something that looks and acts like a ordinary dense multi-dimensional array is a transformation that is out-of-scope for us.

E.g., if the array is stored as a run-length encoded vector, then it is DFDL's job to describe this run-length encoded vector, but not to project/transform it so that it can be accessed in a manner that hides the run-length encoding and makes it look like an ordinary dense array.

(I actually believe hiding sparse array implementations behind a dense-array facade is generally not advised. Algorithmically you must operate on the sparce representation anyway for efficiency. )

Suggested Conclusion: we can just say that we don't do multi-dimensional arrays because it is out-of-scope for us.

Comments?

...mikeb