Additionally there is an indication in the DBD. It follows that a REORG will standardize the row lengths and remove the variable length row indicator from the row header, but is the row now really treated as a fixed length row, or is a MODIFY also needed before these rows are treated as fixed length rows? And if so, what if you don't use DB2 Image Copy to backup your data? The documentation states that MODIFY must find at least one COPY row in SYSCOPY before it will maintain the DBD and log range table. We are on version 8 of DB2 for z/OS.
A subsequent REORG instantiates the new column in all rows, but it does not turn off the OBDREVLF bit. A MODIFY that is run after the reorg and that deletes all recovery resources prior to the reorg does turn it off.
This is the way it works prior to DB2 V8. Haven't tested in v8, but I doubt this has changed.
Special thanks to Michael Murley from BMC Software R+D for his assistance in preparing this answer.
This was first published in January 2005