Position in an MSDB

Issuing a DL/I call causes a position pointer to fix on the current segment. The meaning of next segment depends on the key of the MSDB.

The current segment in a non-terminal-related database without LTERM keys is the physical segment against which a call was issued. The next segment is the following physically adjacent segment after the current segment. The other three databases, using LTERM names as keys, have a current pointer fixed on a position in the ECNT table. Each entry in the table represents one LTERM name and segment pointers to every MSDB with which LTERM works. A zero entry indicates no association between an LTERM and an MSDB segment. If nonzero, the next segment is the next entry in the table. The zero entries are skipped until a nonzero entry is found.