Maybe you did get or you will get an issue with the date command in AIX.
expected behavior, Linux
$ TZ=NZST-12NZDT,M10.1.0/2,M3.3.0/3 date
Sat Mar 17 00:14:54 NZDT 2012
$ TZ=Pacific/Auckland date
Sat Mar 17 00:14:58 NZDT 2012
unexpected behavior, AIX
$ TZ=Pacific/Auckland date
Sat Mar 17 00:15:50 GMT+13:00 2012
$ TZ=NZST-12NZDT,M10.1.0/2,M3.3.0/3 date
Fri Mar 16 23:15:52 NZST 2012
The consequence : date, and all other unix commands like ls, who, ps that display the date in human readable format, and all programs that use ctime are affected
$ TZ=NZST-12NZDT,M10.1.0/2,M3.3.0/3 perl -e 'use POSIX;print ctime(time)'
Fri Mar 16 23:19:51 2012
Reference and link to the fixes : www-01.ibm.com/support/docview.wss?uid=isg3T1013017