You can edit character and hexadecimal representations of binary data for a field; however, to do so, you must have a defined segment layout for the segment occurrence. When you have finished editing fields for the segment occurrence, you can issue an ISRT or REPL DL/I call. You can undo segment buffer edits up until the point when you issue the ISRT or REPL call.
You can edit data from either of these two places within the IMS Database Editor:
When you have finished editing a field, you can save your edits in the segment buffer by pressing Enter. This updates the Segment Data area in the left-hand pane. You can undo the edits you have made to a field by pressing Escape instead of Enter.