winged twilight

What the hell is a GMST?

by Argent

Many of you know about the evil GMST entries that find their way into mods, but I still see this question being asked a lot, and I'm still downloading mods that contain them. So hopefully this article will clarify the issue once and for all.
Game Setting (GMST) records are entries that contain game information required by Morrowind. Some of them contain numerical values for armor and weapons, movement and abilites, game data relating to view distance and gamma settings, while others simply contain the names of skills or spells.

Back to Top Contamination
GMST contamination first became apparent with the release of Tribunal, where it was found that saving a plug-in file without having Tribunal loaded resulted in erroneous GMST entries being dumped into that file.
This contamination breaks the Summon Fabricant spell and changes the names of the Seller Max (to Max Sale) and Share (to Companion Share) buttons. Bloodmoon added another 61 GMST entries bringing the total to 72. 
The origin of these entries is the Construction Set executable file itself, and has nothing to do with any of the master (esm) files. This can easily be proven by loading the CS.exe file, and then saving a file without loading any content. The result is about 80+ kb of GMST entries (1400+), all with incorrect values. These incorrect Morrowind GMST values manifest as a widespread corruption of text strings throughout the game, the most notable is having the letter 's' prefixing every skill and ability.

These 'bogus' entries appear only when the Construction Set cannot find the corresponding GMST value in a master file (which contains the correct values for each).  This is why the problem was first encountered after Tribunal was released.  Many people continued to make Morrowind only mods with Tribunal patched versions of the Construction Set.  As some of the new functionality added by Tribunal required game setting variables, they were patched into the CS.exe file.  Those making Morrowind only mods would therefore not load Tribunal, which contained the correct GMST values, and hence the incorrectly defined ones were quietly saved into their plugin files.
So to simplify:  Official.esm NOT loaded = GMST contamination

Back to Top Mod Makers
If you make mods for Morrowind you need to be aware of the implications of loading or not loading an official ESM file that you have installed on your system.
Whenever you save a plug-in, that mod becomes dependent on all ESM files that were loaded into the Construction Set. This is fine if you intend to use expansion material in your mod, but if your mod does not use expansion items or script functions, it is preferable to only keep the Morrowind dependency.
However, not loading one or more installed expansion ESM files leads to GMST contamination, and you as a modder need to be aware of when these entries are being dumped into your plug-in file, how to avoid them and how to remove them.

Back to Top Avoiding
The only way to avoid this problem is to have ALL installed official ESM files loaded, or run several different installations for corresponding expansion packs.
If you choose to load all expansion .esms, the mod will then become dependent on those master files. Once the mod is completed, the unwanted Parent Master entries can be removed. This is fine if you know you are not using any items or script functions from the ESM file you are removing, but it is not always possible to determine what item belongs with which ESM file. Removing a dependency when the mod uses those items is a sure way to corrupted your file.

Back to Top Removing
There are several ways in which these GMST entries can be removed from a plug-in file, but using the 'Details' section of the Construction Set is not one of them. The GMST entries can be toggled as ignored, which is fine when playing the game, but as soon as the mod is saved in the editor again, the entries are re-entered into the file.
There are several utilities available that can permanently delete GMST entries from a file. Enchanted Editor, TES Plug-in Conflict Detector, TES Advanced Mod Editor, TESTool and GMST Cleaner are all capable of removing these unwanted GMST entries from a file.

Back to Top Mod Users
If you use mods, it's always a good idea to scan new mods for any possible GMST contamination. Many people still do not realize they are being included in plugin files, and even those that do know can sometimes forget to remove them (especially for rushed updates) before deploying.
If you have already included a contaminated mod in a savegame, I recommend NOT deleting the GMST entries in them. Modifying a plugin file once it is included in your save game can lead to a Dirty Save. This occurs because the data stamp on the file is modified, which then changes it's position in the load order. When this happens, the game cannot match cell reference indexes with the file that it originated from, and you end up with two objects instead of one.
To fix this, ManaUser has created a very useful little mod called QuickFix. This mod loads last and 'resets' the GMST values to their correct values.

Back to Top Total Conversions
If you are making a total conversion, it's important that you include all of the CORRECT Morrowind GMST values. Excluding the GMST entries has the same result in-game as including incorrectly defined ones in your master file. This is especially important if you are creating your TC files completely from scratch. The easiest way to obtain the GMST entries from Morrowind.esm is to use the import/export feature of the Construction set. Simply export from MW.esm to a text file, and then import the text file to your own master file. If you have already started a TC from scratch and already have these incorrect entries in your files, you can load up your TC file AND Morrowind.esm into the CS and save. This will update all bogus GMST entries to their correct value, but it will also make you file dependent on Morrowind.esm. This dependency can be removed from your file with the Morrowind Enchanted Editor or The Elder Scrolls Dependency Tool Kit.

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