What does PDA, CSC mean? which firmware do I choose

I want to upgrade my firmware but am unsure about the PDA and CSC.
I am currently using :
model number SM-N7505
android version: 4.3
baseband version: N7505ZHUAOC2
Kernel: 3.4.39-2823447
Build: JSS13J.N7505ZHUAOC2

I was looking for the PDA, CSC but I can't find a corresponding country/region. There is no ZHUA country so was wondering if anyone could help.
I understand that the last 3 letters refer to the time but the region is a mystery to me.