Background: I like the look of old-style numerals in text, but they look bad in acronyms or other all-caps blocks, so I’d like to switch to lining numerals there. I couldn’t find an all-LaTeX way to do this so simplest way seemed to be a filter. I want to match words containing and only containing capital letters and numbers and surround them with \liningnums{}

For example:

NUMBER1 -> \liningnums{NUMBER1}

2022 -> 2022

A1B2C3 -> \liningnums{A1B2C3}

A1b2c3 -> A1b2c3

I’ve played around a bit but don’t know enough Lua or Pandoc internals to get there. I have patterns to check the words but haven’t managed to successfully add the latex macro. Can someone point me in the right direction?

Thanks!