Please see the PUMA Pfizerpedia page for up to date details.
PUMA-REG
PUMA-MSS
The PUMA Molecular Structure Search (MSS) is the service where you search for molecules. This service is a replacement for the Chemical Structure Services (CSS) and is used within applications such as CeN, GCSW, and D360 to view or search for molecules.
PUMA-RS
The PUMA Research Services (RS) is the place where you can retrieve information on your molecules. This service has been updated to retrieve information from the Molecular Entity Data Store (MEDS) which contains all metadata related to the Molecules you have registered.

The Research Services Pfizerpedia entry can be used to learn how to programmatically use RS within your application.