To the best of knowledge:
The SOC cartridge was originally developed for an OCONUS military special operations force for use in MP5s, and has been marketed to US LE that perform maritime/water enforcement.
My rep at ATK stated that the waterproofing is for dive operations (it has been called "Dive Ammo" in their catalogs) and exceeds the moisture proofing on their standard LE Gold Dot offerings. The original product flyer showed MP5 mags loaded, lying in a fishtank).
When the stuff first came out CONUS (2005?) I got samples from ATK and I think I still have a box. I'll get the info off the labels/flyers and post it this weekend if it's worth noting.
The spec for the round I saw was faster by 100+fps than their regular 124gr GDHP, but this may be due to longer test barrel, or maybe just a 'warmer' load for the contract spec.
I'll send emails for more info when I get the chance, but more than likely the cogniscenti here at IAA will have more info before I get a reply.
Lew, FYI I haven't received any further replies on the Taiwan NPA 9mm; hopefully you found what you were looking for.