Red Alert : IMS - potential data corruption

It's been a couple of months, but here's a new red alert concerning users of IMS Version 9.1 using a PHIDAM database. There're more details on the page describing this alert. Don't let the title confuse you because somehow they took over the title from the previous one, but you're on the right page. Here's a quote of the description and the recommended action.

DESCRIPTION:
A defect was introduced by PTF UK25149. The PTF UK25149 was superseded by PTFs UK26128, UK26164, UK27311 and UK27490. If any of these PTFs are applied, then a retrieval of invalid data can occur. Application programs may propagate the incorrect data into another database management system causing data corruption. The incorrect data returned to the application program can only be detected if the application program logic validates the data and finds the retrieved data falls outside of the valid ranges.
The exposure exists only when all of the following conditions are met:

• Using IMS Version 9.1
• Using a PCB with read-only (PROCOPT=GOx) and issuing GN calls against records in a PHIDAM database
• Using a DBD with twin backward (TB) pointers on the root segment
• PTFs UK25149 or UK26128 or UK26164 or UK27311 or UK27490 are applied

RECOMMENDED ACTIONS:
Remove PTF UK25149 or UK26128 or UK26164 or UK27311 or UK27490; or apply the solution in PK49955/UK28788.

All the recent red alerts can be found over here.