Logistic regression: Select or change reference group

I am new to RapidMiner but have been working with logistic regression in SAS for years.  When working with categorical attributes in logistic regression, how does RapidMiner choose which cateogry to be the reference category?  Is it possible to change this to assign a different reference category?

For example, say I have Race in my model with five possible values of white, black, asian, other, and unknown and RapidMiner is assigning a weight of 0 to black (with all other weights being relative to black) but I want to change it so asian or white is the reference group with a weight of 0.  Is there a way to do this?

Thanks.