Vim syntax and indent settings for NONMEM.

Use your favourite plugin manager. E.g., with vim-plug place this in your .vimrc:

Plug 'timwaterhouse/vim-nonmem'

… then run the following in Vim:

:source %
:PlugInstall

I've purposely avoided adding any kind of filetype detection, due to the myriad conventions for naming NONMEM files. So you'll probably want to add something like the following in $HOME/.vim/filetype.vim (or elsewhere, see :help new-filetype) to appropriately set the filetype to nonmem:

if exists("did_load_filetypes")
  finish
endif
augroup filetypedetect
  au! BufNewFile,BufRead *.mod,*.lst setfiletype nonmem
augroup END