In 2012 I started a discussion with this title. (See https://groups.google.com/forum/#!topic/mainframe-assembler/W3oDT_txPWo). As it seemed to be fairly well received, but not yet implemented, I decided to open an official RFE for it: http://www.ibm.com/developerworks/rfe/execute?use_case=viewRfe&CR_ID=85682. (Make sure you are signed on with your IBM user ID before clicking.)
Please vote if it seems useful.
