--------      --------      --------      --------      --------
|      | ---> |      | ---> |      | ---> |      | ---> |      |
|FRONT |      |PARSER|      | OVQP |      |DECOMP|      | DBU  |
|      | <--- |      | <--- |      | <--- |      | <--- |      |
--------      --------      --------      --------      --------
PTAB INFO
FRONT	nothing
PARSER	overlay id's, decomp id
OVQP	nothing
DECOMP	overlay id's
DBU	ksort pathname