[Cellar] generate a version (0, 1, 3) and version 4 FFV1 document from single source

[Dave Rice <[e-mail]>]

Hi cellar,

I’ve drafted a pull request at https://github.com/FFmpeg/FFV1/pull/102 based on Michael Niedermayer’s suggestion https://github.com/FFmpeg/FFV1/pull/93#issuecomment-356348383 <https://github.com/FFmpeg/FFV1/pull/93#issuecomment-356348383>. This attempts to create a method where the FFV1 specification may be worked upon within a single document while the parts that only relevant to the version 0,1,3 document are suppressed from the version 4 document and vice versa. To do this I’d created a method of ending lines with with "{V3}” (for version 3 and prior) or “{V4}” for version 4 or greater. I think this will help enable work to progress on the version 4 document as defined in our charter even while the version 0,1,3 hasn’t been reviewed by the IESG yet.

However some IETF questions:

In the PR the new outputs of the Makefile are:
draft-ietf-cellar-ffv1-01 (defines version 0, 1 and 3 of FFV1)
draft-ietf-cellar-ffv1-v4-00 (defines version 4 of FFV1)

This keeps the same id for version 0, 1, and 3 but would something else be more clear? Any examples of naming when IETF defines multiple versions of the same thing in separate documents?

I’ve separated the document version numbers for each, so draft-ietf-cellar-ffv1 stays at 01 and draft-ietf-cellar-ffv1-v4 starts at 00. Work?

In the version 4 output there are references to exceptions defined in our work on version 0,1,3. These include all lines starting with “Background”. I suggest resolving these in a subsequent commit, but perhaps the version 4 document need not include these but could only reference exceptions existed in prior version.

Best Regards,
Dave Rice