What is the purpose of the different names for the TIDDAQUx and TIRDAT2x modules?
TIDDAQUE controls the internal delete/disassociate queue that is built at runtime. When the delete is made, Gen will chain through all the relevant Referential Integrity Triggers associated with the cascade, writing the key value of any data to be deleted or nulled to the queue by calls to TIDDAQUE. If upon getting to the bottom of the queue it is valid to process the delete, then the queue is used as the source information for the actual data deletes or updates. If you look at generated source for entity triggers you will normally see a call to this name TIDDAQUE. There is TIDDAQUC for CICS and TIDDAQUI for IMS.
TIRDAT2x is a user exit that allows the user to modify the value returned from the date and time services to the Gen application. The date and time service module TIRDAT is not directly modifiable, so the exit is provided. TIRDAT2C is for CICS and TIRDAT2I is for IMS.