P command code

Ordinarily, IMS sets parentage at the level of the lowest segment that is accessed during a call. To set parentage at a higher level, you can use the P command code in a GU, GN, or GNP call.

The parentage that you set with P works just like the parentage that IMS sets: it remains in effect for subsequent GNP calls, and is not affected by ISRT, DLET, or REPL calls. It is only affected by GNP if you use the P command code in the GNP call. Parentage is canceled by a subsequent GU, GHU, GN, or GHN.

Use the P command code at only one level of the call. If you mistakenly use P in multiple levels of a call, IMS sets parentage at the lowest level of the call that includes P.

If IMS cannot fully satisfy the call that uses P (for example, IMS returns a GE status code), but the level that includes P is satisfied, P is still valid. If IMS cannot fully satisfy the call including the level that contains P, IMS does not set any parentage. You would receive a GP (no parentage established) if you then issued a GNP.

If you use P with a GNP call, IMS processes the GNP call with the parentage that was already set by preceding calls. IMS then resets parentage with the parentage you specified using P after processing the GNP call.

For example, if you want to send a current bill to all of the patients seen during the month, the determining value is in the ILLNESS segment. You want to look at only patients whose ILLNESS segments have dates after the first of the month. For patients who have been to the clinic during the month, you need to look at their addresses and the amount of charges in the BILLING segment so that you can print a bill. For this example, assume the date is March 31, 1993. Issue these two calls to process this information:

GN    PATIENTb*PD
      ILLNESSb(ILLDATEb>=19930301)
GNP   BILLINGbb

After you locate a patient who has been to the clinic during the month, you issue the GNP call to retrieve that patient's BILLING segment. Then you repeat the GN call to find each patient who has been to the clinic during the month, until IMS returns a GB status code.