Manual:$wgSharedLatin1

Details
If you operate multiple wikis, you can define a shared upload path using $wgSharedUploadPath. If $wgUseSharedUploads is set, the wiki will look in the shared repository if no file of the given name is found in the local repository (for, [[Media:..]] links).

Thumbnails will also be looked for and generated in this directory.

Uploads to the wiki will NOT be put there - they will be put into $wgUploadDirectory.

Set this value to true if the repository uses latin1 filenames.