Cisco xr ucm versions with base

[Nostr_nostr]

Could anyone possibly explain what "base" postfix means in Cisco IOS XR and Cisco UCM versions?

For example: https://bst.cloudapps.cisco.com/bugsearch/bug/CSCux95576

Here we can see affected release named "5.3.1.BASE".

Or in CVRF for https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/Cisco-SA-20140212-CVE-2014-0722 we can see 10.0 Base and 10.0(1) Base

What alternative postfixes can be there, except "base"?

Yours faithfully

Alexander M