Qualified calls
When a call is issued for a root segment and the call is qualified on the root segment's key, the way in which the database record containing the segment is found depends on whether the database is HDAM, PHDAM, HIDAM, or PHIDAM.
In an HDAM or a PHDAM database, the randomizing module generates the root segment's (and therefore the database record's) location. In a HIDAM or a PHIDAM database, the HIDAM or PHIDAM index is searched until the index segment containing the root's key is found.
Once the root segment is found, if the qualified call is for a dependent segment, IMS searches for the dependent by following the pointers in each dependent segment's prefix. The exact way in which the search proceeds depends on the type of pointers you are using. The following figure shows how a dependent segment is found when PCF and PTF pointers are used.
