/usr/share/vim/addons/ftdetect/stp.vim is in systemtap-common 2.6-0.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | augroup filetype
au BufNewFile,BufRead *.stp set filetype=stp
augroup end
|