Joined: 13 Jun 2007 Posts: 826 Location: Wilmington, DE
Command "P" sets parentage at the level of the SSA where it is coded.
The pathcall command code "D" can be used to insert a path of segments. Only one of the SSAs would contain the "D" command code - the SSA corresponding to the first segment in the path to be inserted.
Do you have an IMS program that is using "U" and/or "V" command codes? In all my years of IMS, I have never used or seen any IMS programs that use the following 2 command codes. Remember that most of the life of a program is maintenance. You need to think of the most straight forward - easiest to maintain method. If you could tell us what you want to achieve, we can give you examples.
Th "U" command code may be used in lieu of building a qualified SSA when you want a call processed maintaining current position at the level(s) speicified by a "U". Example: you would issue a GU for the parent segment - issue GNP with the "U" command code.
The "V" command code is the same as the "U" command code, except that the command code is set automatically at all higher levels in the call.
The U Command Code
As IMS satisfies each level in a retrieval or ISRT call, a position on the segment occurrence that satisfies that level is established.
The U command code prevents position from being moved from a segment during a search of its hierarchic dependents. If the segment has a unique sequence field, using this code is equivalent to qualifying the SSA so that it is equal to the current value of the key field. When a call is being satisfied, if position is moved to a level above that at which the U code was issued, the code has no effect for the segment type whose parent changed position.
U is especially useful when unkeyed dependents or non unique keyed segments are being processed. The position on a specific occurrence of an unkeyed or non unique keyed segment can be held by using this code.
The V Command Code
Using the V command code on an SSA is similar to using a U command code in that SSA and all preceding SSAs. Specifying the V command code for a segment level tells IMS that you want to use the position that is established at that level and above as qualification for the call.
Using the V command code is analogous to qualifying your request with a qualified SSA that specifies the current IMS position.