It's certainly set up for extensibility, although some areas are a pain (e.g. blank lines may be ignored entirely, change vertical spacing or change semantics, that can be annoying).
The toolchain is also fairly complex and very badly documented (Sphinx itself is better documented than docutils, but either way you end up wading through piles of code to understand what happens, why, and what's available in the applicative context of your extension)
It's certainly set up for extensibility, although some areas are a pain (e.g. blank lines may be ignored entirely, change vertical spacing or change semantics, that can be annoying).
The toolchain is also fairly complex and very badly documented (Sphinx itself is better documented than docutils, but either way you end up wading through piles of code to understand what happens, why, and what's available in the applicative context of your extension)