What does cleaning an .esm file do exactly?

[arandommodder12]

I just got Anniversary Edition, and SSEEdit is on it's knees begging me to clean the main files, creation club files and some of my installed mods as well. It's amassed to well over 40+ dirty files in total. I'm gonna do it of course so that LOOT shuts up but I am curious, what does cleaning the file do exactly? Any modders out there able to tell me what's going on??

[IsharaMeradin]

Cleaning is more important for mod plugins (including CC) than it is for the DLC ESM files. Cleaning removes records that are identical to the master file(s) aka ITMs. Cleaning also un-deletes deleted references and lowers them out of sight aka UDRs.

 

What do these steps actually do?

 

When a plugin contains a record that is identical to the master files and that plugin is the priority winner, its version of the record will overwrite any other plugin that may have made an intentional edit to said record. Due to multiple edited records and multiple potential masters, plugin sort order cannot always resolve such conflict. Thus removing the records that are identical to the master file(s) lightens the burden on sort order and patch plugin necessity. That said, there are a small number of mods that do intentionally create ITMs as they need stock values for their particular vision. These types of mods usually state that they should not be cleaned.

 

When a plugin deletes a reference record found in the master file and that reference record is referred to by another record or script, the game will crash when attempting to load or access that deleted record. By restoring the reference record and lowering deep below ground, the game will not crash when the reference record is loaded or accessed. The player just won't see anything as it is out of sight.

 

Mod authors should clean their own files before releasing but there is never a guarantee that an author has done this unless explicitly stated.

[xkkmEl]

[ See Ishara's response] Edited February 10, 2023 by xkkmEl