Classifications

I'm thinking of entering my first race this weekend and I have a quick question.

This may be a Colorado thing, but I seem to not understand the ACA classification system. I see on the crit I want to enter (http://americancyc.web152.discountasp.net/Schedule/2008Flyers/2008_Primus_Criteium.pdf) That they have a SW 4 and an SM 4. I'm assuming SW is women's and SM men's but I don't know and would rather not feel the embarassment of showing up at the wrong time.

Can someone help me out please? The race is on Sunday and I'm panicking a little bit. I realize that this is a small detail, but I'm racing for the first time and don't want to look like a complete noob.

Thanks Much
James