IDOC Filtering for DEBMAS

I am currently using change pointers to trigger the DEBMAS IDOC. I need to be able to filter a range of customers that are not required to be sent. These customers have a defined class type, so it would be ideal to prevent these from going through with a <> filter.

I'm looking into the Distribution Model filter, but the options appear limited to Function, Company Code, Credit COntrol Area, Division, Sales Org, Dist Chnl.

Any ideas to exclude this type of customer from the IDOCs being processed would be very much appreciated.

Thank you!

Jaime