Is the THHN and THNN designation equivalent, or is there even a THNN designation?

Due to convience I ordered wire over the internet- THHN. The lable indicates THHN but the wire marking indicates it is THNN. It also has the usual THWN-2 marking. I can't find the THNN designation in NEC table C.1. The wire is Southwire produced on 4/8/11, the Southwire site makes no reference to THNN, and a web search reveals nothing. Any ideas?

There is no THNN. If it says this it is a typo of sorts.
Most all newer THHN wire is dual rated THWN, so what you have it normal.

Stan,
I figured a typo error since all of the other specs (MTW, gas/oil resistant, etc) check out, but wasn't totally sure if I was missing something. Maybe that's why the wire was reasonalby priced.