Wirelessly posted (Moto Droid Bionic: Mozilla/5.0 (Linux; U; Android 2.3.4; en-us; DROID BIONIC Build/5.5.1_84_DBN-74) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1)
While there are some generally accepted APCO 10-codes promoted at the national and state levels, there is no mandate to use them. In my area the codes have been replaced by plain English, e.g., the dispatcher's "10-4" has been replaced by "ok". Generally, context lets one figure out meaning. Just listen a while. HTH.