B.A.S.I.C. I encountered a few thousand lines of code from the 80's I need to edit, and would like to save a couple hours it may take me to roll my own VIM syntax defs file.
VIM ships with basic.vim
now. This has been updated in 2011.
https://github.com/vim/vim/blob/d07969093a9b3051511c478d71c36de6fc33c0d6/runtime/syntax/basic.vim