Sometimes it is necessary to limit the creatable elements on a page. This is especially useful if you only want to save specific elements within a SysFolder, e.g. within "users" there should be only users.
Within the TSConfig of the appropriate page add the following TypoScript having db_tablename be the database table with the elements you want to limit to:
mod.web_list.allowedNewTables = db_tablename,db_tablename_2