"modded" = modified.
In most cases, in officially delivered update from FSC there is nothing more but some options just invisible, not removed.
Well, if you'll use Google, and if you kave knowledge about bios structure, you can unlock it
I'm fresh owner of Pa1538, so i didn't looked into it yet, but with Amilo A7640 it's working fine.
One important warning: even if you'll have the pathed/modified for another Pa1538 one, you have to be careful. Here's an example: first time with Amilo A7640 I screwed up, bcs another revision of mainboard. Fortunately, one of my polish friends is more familiar with me, and he flashed it with eeprom programmer correctly.
Otherwise, if something will go wrong - you have to pay to FSC service guys :-/