GibStats comes with a list of the death messages of some mods such as regular DM or CTF, etc. GibStats can therefor analyse, "understand" logs containing these messages. GibStats cannot correctly analyse logs containing messages which have not been included in the lists. Therefor you have to produce a file which includes these messages if you want to add client log support to your mod.
The format of such a support file and what information it has to contain is explained in the help file of GibStats ("How To" / "Customizing GibStats")
GibStats now supports multiple *.gsl files. The mod author (or anybody else) has to produce a file containing the mod specific information, called [ModName].gsl. The file needs to contain every obituary used by the mod, including the original messages by id (if they are used by the mod). This file only needs to be copied into the GibStats directory. The user chooses the this file before reading the client log into GibStats.