/usr/share/highlight/langDefs/bbcode.lang is in highlight-common 3.41-1.
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 8 9 10 11 12 13 | Description="BBcode"
Keywords={
{ Id=1,
Regex=[[ \[\/?\w+|\] ]],
Group=0,
},
{ Id=2,
Regex=[=[#[[:xdigit:]]{6}]=],
},
}
IgnoreCase=true
|