I don't believe you can do that.The search_custom.xml file provides for the drop-down menus in the EA search section, the FieldMapping.xml requires that you define each and every EA you want to index, including their type.Note - EAs of String type only allow you to search for "All Words" and does "fuzzy" matching - so it's not very good for IDs that are string-oriented (e.g.: "X74J3")There are a number of other issues with Search which I recently posted about that you might want to look at before trying to do too much with it...