Use truncation symbols to allow for various word forms of your search terms. Symbol Definition Example Retrieval ______________________________________________________________________________ ? Any number of characters STEROID? STEROID (including none), at the STEROIDS end of a term* STEROIDAL ______________________________________________________________________________ # One or zero characters, VAP#### VAPOR at the end of a term VAPORS VAPOUR VAPOURS ______________________________________________________________________________ ! One character, at the end WOM!N WOMAN or within a term WOMEN ______________________________________________________________________________ * In the Basic Index of the CA file, truncation is allowed at the beginning of a term (?BACTERIA) ------------------------------------------------------------------------------ Reproduced with the permission of CAS, a Division of the American Chemical Society, from "Tips for Searching the CA & Registry Files." (CAS8721-0894)