I have seen other carriers do the same...
At IAH or EWR, you will sometimes see a ground stop "COA + BTA only" or "COA only" or "BTA only"
BTA = ExpressJet
For a full overview, checkout:
http://www.fly.faa.gov/ois/
When I toured the DAL ramp tower at CVG, they were actually using the above page as one of their monitoring tools.