Cross-facing.

[EternalRage]

I do it after sprawling or to stop single legs. Also if I'm in a position like high mount and opponent's got both arms clasped together behind my back and won't give me the space to isolate an arm to work with, I will put my forearm across his throat and push till he gives.

[DaChinkOfSteel]

I go either way, I'll use it in the "wrestling" sense to move somebody's head where I want it to go, but I won't use it to chafe a guy's face for the purpose of pain; largely because I look at it like, "I'll eventually meet some tough-guy who I can cross-face all I want and it won't do anything"...that just goes for normal BJJ training, of course if it happens during scrambles purely unintentionally...I assume if I trained MMA (which I don't) it would be different and I would use cross-faces to grind and stuff, rather than just move the head around...

My policy kinda goes like this when it comes to "frowned upon" vs. "school rules"...just ask whomever you're rolling with whether or not s/he's ok with whatever...if I cross-face somebody on accident, I'll apologize and if they respond with "That's fine, I don't mind going hard" or whatever, then I'll be a little less conservative about cross-faces...if they wince in pain and are like, "It's ok, that happens" then I'll go out of my way to make sure THEY'RE COMFORTABLE rolling with me...afterall, training partners are your most valuable asset.

So communication is key...some people don't mind footlocks, some do, some just don't know how to defend, etc...it's all a matter of talking with your partner...it's no different than them saying "Hey, I have a hurt shoulder, do you mind if we just really work on technique and go a little lighter?"...

My 2 cents...