More information please: what exactly does "sexual assault" mean?

We're being warned about a man connected with a series of sexual assaults on the Yonge subway line:

Okay, I ride the Yonge subway line, am I at risk?

He tends to approach women between the ages of 20 to 40 years old, with slim to average builds, and long, black or dark brown hair.

Between the ages of 20 to 40? Check. Slim to average builds? For slightly optimistic values of "average". "Long, black or dark brown hair"? Check.

Oh, shit, what's going to happen to me?

The man stands behind the victims on crowded trains and engages in what police loosely term “sexual acts.”

Meaning what, exactly? Is he going to try to stick his penis in me, or is he going to wank at me? Or is he going to do something else I haven't anticipated?

As part of the target audience, I'd very much like to know what I'm in for so I can be prepared. I'd like to start thinking about how I might defend myself against whatever these loosely termed sexual acts are. I'd like enough information to be confident in shouting in a crowded train "Stop him, that's the guy!" rather than getting a false positive on some guy who just innocent stumbled when the train changed speeds. I'd like enough information to be able to recognize halfway across a crowded train if he starts doing whatever it is he's doing to someone else.

I feel like the Toronto Police are not giving me enough information to protect myself and my fellow citizens, or to help positively identify the suspect, and I feel like I could do these things better if they'd give me a more specific description of what to expect. Yes, a more specific description is probably distasteful. That's why I want to read about it in my morning paper rather than experiencing it on my morning commute.