[EAS] Duplicate CAP alert criteria

[Dave Turnmire]

I have long been familiar with the criteria used by decoders to identify 
"duplicate" S.A.M.E. alerts.  But... a recent event caused me to wonder 
about what the criteria is for recognizing duplicate CAP alerts.

Last week a bug in the software used in our state caused the user to be 
told "message not sent" after they pressed the Send button. So... they 
tried again.  And then another staffer sent a third. Well... fortunately 
it didn't involve ICBMs... but it was three RMTs sent in a row to much 
of the state and you know how broadcasters like that.

In the rush to get the RMT out "on schedule" the third one used another 
template than used for the first two.  The ONLY difference was what the 
text and audio indicated the originating party was (we have a primary 
and backup CAC).  And... they immediately realized they had used the 
wrong template so then issued a "cancel" message. All of this via 
IPAWS.  Well... I just discovered there was one more difference in the 
third case... there was a typo in the template for the third RMT such 
that it's "title" was "Required Weekly Test" rather than the correct 
"Required Monthly Test" (since corrected).

So... setting aside WHY all of the above happened (we're addressing 
that) is the question of WHY decoders behaved as they did.  And to what 
extent that response is consistent between manufacturers.  What happened 
on my DASDEC is it recognized the second RMT as a duplicate and didn't 
forward it.  But... it didn't recognize the third one as a duplicate and 
DID forward it.  I think at least some SAGE boxes behaved similarly, but 
I'm not sure.

All three of these alerts were sent within a 41 second time span. At 
least in some cases, the second one was considered a duplicate. All 
three had DIFFERENT "Message Identifiers".  As far as I can tell, the 
first two were identical in all other ways.  The third had a different 
audio URL and "Description" text.  And what ever CAP calls the 
"title".    Which of those three differences (if any) would cause the 
decoders to identify it as a unique message?  And what needs to be 
different to have caused the first two messages to be considered 
unique?  Obviously the message identifier wasn't enough... at least in 
some cases.

Any input Ed?  Harold?

Dave