Hi. I'm working on https://github.com/jgm/pandoc/pull/1968, and I've got some questions.

Some styles in reference.docx are marked as custom, some are not. Some of those not marked custom are recognized by Word as built-in. Some are not, however. Word automatically marks those as custom, but this introduces unnecessary ambiguity. Furthermore, some styles not recognized by Word as built-in actually duplicate built-in styles, and could be renamed to reflect that.

Here is a list of styles I'm most concerned about:

these are either ambiguous (again, meaning that they are neither custom, nor Word defaults), duplicate default Word styles, or both.

So the question is, what should be done with them? I've got the following options:

1. Update reference.docx to define ambiguous styles as custom. Do nothing more. This is a quick-and-dirty solution.
2. Replace styles in reference with word-recognized ones as best I can, set those I can't as custom. This is a longer path, but leading to hopefully better user experience.
3. Do nothing at all, and hope for the best. This will likely lead to 'surprises' in the future, and not the pleasant kind, I fear.

First two options require significant updates to reference.docx though, and option 2 is not strictly backwards-compatible with pandoc-created docx (although it'll likely be a couple of styles, not much more).

So, what are your thoughts on this matter?