/usr/share/source-highlight/lsm.lang is in libsource-highlight-common 3.1.7-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | # Linux Software Map language definition
keyword = 'Begin[[:digit:]]*|End'
type = '^[[:word:]-]+:'
include "url.lang"
|