. all documentation lines begin with --
. first line is function name, should match filename
. groups are set with @group:
. required groups are: short, inargs
. optional groups are: related, external, note, longdescr, outargs
. There may be multiple inargs, one for each set of accepted args

in text blocks, empty line is paragraph break.
*arg* is a reference to an argument.
constants are in all caps.

inargs: comma separated list, type:name
where type is one of:
int, bool, float, str, vid, vtbl, func, aid, atbl

outargs group: set if function returns anything

external group: yes, no or missing (=no), means that the function
is part of allowed external invocations or not

related group: comma separated values

