- From Solaris 2.5.1 Server Release Notes:
Previous Solaris 2.x software releases used 32-bit data types to contain the user IDs (UIDs) and group IDs (GIDs), but UIDs and GIDs were constrained to a maximum useful value of 60000. In the Solaris 2.5.1 release, the limit on UID and GID values has been raised to the maximum value of a signed integer, or 2147483647."
"Caution - UIDs and GIDs over 60000 do not have full functionality and are incompatible with many Solaris features, so avoid using UIDs or GIDs over 60000. See Table 2-1 for a complete list of interoperability issues with Solaris 2.x products and commands."
- From Solaris 10 System Administration Guide: Basic Administration:
"However, UIDs and GIDs over 60000 do not have full functionality and are incompatible with many Solaris features. So, avoid using UIDs or GIDs over 60000."
- Starting with kernel 2.4, Linux supports 32-bit UIDs and GIDs.