fixed width font for special txt files

[cavelamb]

I would like to be able to use .TXX extension to indicate that Notepad++ use a fixed width font for an otherwise ordinary .TXT file.
But I don’t know how…

[Terry R]

@cavelamb

There are some past postings which border on the area you refer to. i don’t personally use UDL (user defined language) or alter the fonts at all but hopefully these posts can enlighten you a bit.
@PeterJones :
https://notepad-plus-plus.org/community/topic/15988/language-not-being-saved-with-file
and
https://notepad-plus-plus.org/community/topic/16889/changing-font-size

@guy038 :
https://notepad-plus-plus.org/community/topic/12104/need-help-to-find-different-font-in-same-text-file-through-notepad/2
and
https://notepad-plus-plus.org/community/topic/16474/please-tell-me-how-to-display-ipa-characters-properly-with-a-monospace-font/2

Have a read there and maybe there might be some good info to help you.

Terry