ChemDraw DDE Commands

*Either the Execute or Request command type may be used for any entry labeled "Execute". Request mode must be used for those commands labeled "Request". The Request method allows ChemDraw to complete the DDE command before it ends, and is therefore necessary for commands that produce output (viz. PIPE, CLEAN and MAKE_METAFILE). The Request format also allows an error message to be passed back to the client, and is therefore the recommended approach. Apart from these considerations the Execute format is simpler to use, and the programmer may choose whichever is more convenient.