Comparing different maintenance levels of the CA Top Secret r15 install library shows many differences.

Document ID : KB000012246
Last Modified Date : 14/02/2018
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Question:

We did a comparison of both the libraries and found that 66 members had no changes. 41 has changes. Why?

Answer:

Previously CA used to provide new functionaliy at new release levels.

CA has changed this. Enhancement are now provided every 3-4 months.

Here are just a few under r15:

TSS MODIFY COMMAND RESTRICTION VIA CASECAUT
ENHANCE TSS COMPARE CMD ADDING ALL ACID TYPES
ENFORCE RPW FOR ANY POSITION IN PASSWORD
REDUCE NUMBER OF STORAGE OBTAINS IN RACROUTE PROCESSING
ADD SAF UID/GID TABLE EXTENSIONS
LEVERAGE 64-BIT STORAGE FOR CERTIFICATE TABLE

Integration with CAs new product CA Data Content Discovery (DCD) which allows you to identify sensitive data in your system which you may not be aware of, so you can secure/protect it.

This is why you have so many difference between your CA Top Secret install libraries.

Under r16, CA Advanced Authentication for Mainframe was introduced in the past few months. It's equivalent to IBM's MultiFactor Authentication, but our is free. IBM charges for theirs. There are many other enhancements for r16 and more to come.