Can't find info on media management options

Is it possible to add more info for the following “Replace Illegal Characters” At the moment I can’t find any info which characters are illegal and what they are replaced with. I for one want “&” replaced with “and”, don’t know if that is covered by the “Replace illegal Characters” or by using “CleanTitle” and therefore used “{Series CleanTitleYear}” up until now which is giving issues with Plex as that is looking for the year in parenthesis.