Possible values in the National Weather Service Alert Feeds

Has anyone been able to find documentation that has the possible values of the CAP fields in the national weather service alert f开发者_如何学运维eeds (sample: http://www.weather.gov/alerts-beta/tn.php?x=0 )?

It would be useful to have software that reacts differently to minor events and major events, as well as different types of events. I suppose its possible to just start recording data and try to figure it out, but severe weather doesn't happen often enough to record all the possible values the NWS uses. Is the XML format based on a known format I'm unaware of?

Of particular interest are the possible values of these fields: Actual Alert Met Expected Minor Observed

A quick Google search led to a link to the schema for the xmlns:cap namespace, at http://niem.gov/niem/external/cap/1.1/cap.xsd. That shows that, for example, the cap:status tag can have a value of "Actual", "Exercise", "System", "Test", or "Draft"; cap:msgType can have a value of "Alert", "Update", "Cancel", "Ack", or "Error"; and so on.