GSS supports single character and multi-character wildcards. The question mark symbol, "?" matches any single character. The asterisk symbol, "*" matches any sequence of characters. Neither of these may be used as the first character in a search term because this results in poor performance. When implementing a search developers should consider whether users should be allowed enter these characters in searches, and if so provide useful online help. Otherwise they can be escaped with an escape character: "\". It may also be useful to check that these characters do not occur at the start of search terms and return a more specific error message to the user than the GSS infrastructure is capable of doing (a generic exception to indicate that the query is invalid will be returned, but the developer implementing the search will be able to add more information regarding which field is invalid).