[EAS] Decoder handling of non-EAS CAP messages

[Sean Donelan]

On Mon, 20 Jul 2015, Ed Czarnecki wrote:
> Put very simply, CAP EAS devices nearly all the IPAWS CAP EAS feed.  If the alert is present in the feed, it's supposed to be there.  The WEA feed is a completely separate messaging path that EAS devices do not have access to.

That looks like a vendor proprietary extension.

Essentially all CAP channels work the same way, if the message is 
distributed through a CAP channel, and it will be processed by every
device listening on that channel.  There is no "BLOCKCHANNEL" parameter.

While there is some filtering by the CAP-EAS devices of their channel, 
i.e. geography or event code, some operators of CAP-EAS device do not 
always filter them.  There are several web sites on the Internet which 
show every IPAWS message distributed through the PUBLIC channel including
tests and administrative messages.  And there was a case of a national 
cable TV provider which had the wrong filters in their CAP-EAS device, and 
re-broadcast the weekly FEMA test.

Simple rule, if you don't want a message processed by other CAP channels,
i.e. CMAS only, do not forward the message to other CAP channels.

Of course, that brings up a secondary problem.  You probably want 
newsrooms at broadcast stations to know about the WEA message, but not
re-broadcast the administrative message.  In theory, CAP can act as a wire 
service to reach broadcasters.  But most Public Information Officers 
already have a private list of contacts at news stations for email or fax 
alerts instead of using CAP.