OBJ ESD records containing CM data provide the CM name, its ESDID, and its length. (Alignment is implicitly doubleword.)
Note that Fortran BLOCK DATA sections can be handled as traditionally "overlaid" SD items if they are specified as follows:
OBJ CM items are mapped onto GOFF format SD, ED, and (if needed) LD records in exactly the same way as are SD parts (shown in Mapping object module ESD SD items), except that the "COMMON Flag" bit is set to B'1'.
Blank COMMON is treated specially by the binder (as it was by the linkage editor). Blank COMMON never has initializing text even if a blank-named control section (Private code) is present.
(The program management binder and the program object format support a much more powerful way to handle "COMMON" or external data previously emitted as OBJ SD items. They are then not mapped by the program management binder as though they were SD items. This avoids the problem of order-dependent behavior in the OM/LM assignment of lengths to CM items with initializing data specified in an SD item.)