From Elendor
Syntax: +BBREADLOCK <name>=<function>
**Admin-only**
This locks reading of a bulletin board to those users who cause the given
function to evaluate to a true value. (See HELP t() for what a true value
is). The enactor is %# as usual. By default, the +bbcreate command sets
this to 1 which allows anyone to read. If you set it to blank, it defaults
to allowing only members of the list set with +bbnotify to read. (If no
+BBNOTIFY list is set, then nobody can read in this case.)
Example: +bbreadlock harad=\[strmatch(get(%%#/culture),*Haradrim*)\]