Preprocessor advisory spec (For recommended handling of preprocessor directives)

I’m currently in the process of building documentation that self updates with information. At the moment I’m just researching what options are out there. However it would be nice if pandoc had something like:

pandoc --variables variables.json -o book.pdf

There is an issue ticket on this in for pandoc.

Still I think it’s a relevant topic for common mark to consider about having some form of preprocessor recommendation that is not part of the main commonmark specification, but is handled by those who deals with preprocessing commonmark files. Stakeholders may include:

How pp deals with preprocessing


This looks somewhat similar to the generic attribute syntax of !type[...](...){...} that I see proposed around here. Would it be safe to just adopt pp’s approach to preprocessing as the advisory spec for preprocessing? Or should we align it more with the generic syntax (Would @jgm pandoc find it easier to parse pp style syntax or is there a safer syntax that won’t add too much complexity to pandoc)?