Solaris 64-bit Developer's Guide

Derived Types

Using the system derived types helps make code 32-bit and 64-bit safe, since the derived types themselves are safe for both the ILP32 and LP64 data models. In general, using derived types to allow for change is good programming practice. Should the data model change in the future, or when porting to a different platform, only the system derived types need to change rather than the application.