Is the ABS clean-out valve plug under the sink reverse thread?

Question:There's only 1 clean out in the entire house. that's under the kitchen sink. the plug doesn't want to budge but I don't want to force it because it's at the end of an "ARM" of ABS that moves when I put pressure on the plug. I don't want to break the arm off and I have no clue how old the assembly is. SO: I was wondering if possibly the plug is reverse thread, or any clues. I've isolated the clog to be right next to the clean out and there are loads of twists and turns getting to it (in the abs) so it doesn't look like getting a snake in there is gonna be possible. I've being trying all morning, but no luck so far. So, ideas on the plug?

Answers:
It is standard right hand thread. Use a pipe wrench to "back-up" the arm that is twisting. You will then use another wrench to unscrew the plug. So, the two wrench handles will be going towards one another when you apply pressure. (The plug wrench should be forced into a counter-clockwise movement & the Back-up wrench should be forced into a clock-wise movement both at the same time)
If you still have no luck and the plug too is ABS then drill several holes into it and break it out of the fitting, then just buy a new one and replace it.