system.sw.os[short] returns ZBX_NOTSUPPORTED on agents running 2.0.2, while 'name' and 'full' return valid values.
Sample:
~ # zabbix-get -s dimholt -k system.sw.os[short]
ZBX_NOTSUPPORTED
~ # zabbix-get -s dimholt -k system.sw.os[full]
Linux version 3.5.1-2-default (geeko@buildhost) (gcc version 4.6.2 (SUSE Linux) ) #1 SMP Fri Aug 10 15:25:03 UTC 2012 (370c9f4)
~ # zabbix-get -s dimholt -k system.sw.os[name]
Welcome to openSUSE 12.1 "Asparagus" - Kernel %r (%t).
~ # zabbix-get -s dimholt -k agent.version
2.0.2