I was wondering the same thing. Our agency said the request was for Caucasian boys between 4 and 7 but didn't specify the job. We walked in to the casting and no one was there. The person who took our information said that the agencies and the client had been pretty selective about how was invited, which was a nice change for us. Lately we've been at a lot of big castings where there were both genders, all ages and all diversities.
Good luck!