[CAP] handling optional fields

[Mick Jagger]

> Hmmm... if implementers start adding new fields with semantics that  
> overlap the existing ones, what happens to interoperability?  How do  
> receivers know what to expect?

I'm not saying a new field, but a custom parameter or other optional field, that is deemed the "HazCollect" field.  If a submitter wants to control the message HazCollect distributes in the truncated versions, then you follow their guidelines for this field.

> > 	All the larger users of CAP, national governments especially, seem  
> > to be keen on taking the standard and adding their own custom  
> > fields, formats, etc to suit their own local needs.
> 
> Really?  Maybe you could provide some examples.  A lot of  
> implementers use the provided <parameter> and <resource> capabilities  
> to provide more detailed information, but this is the first case I  
> know of where someone has unilaterally redefined the meaning of an  
> existing CAP field.

I meant custom fields, ie parameter, resource, area values that suit their needs through a customizable CAP value.  Sorry if it came across as meaning whole new CAP fields.  There is still going to be a mishmash of related custom values and I expect that some aggregators will eventually demand the use of their custom value in order to transition their distribution format.  So in HazCollect's case, they'll take your plain CAP and truncate it accordingly, or use their special value, and get more message control.

I'd like to propose a new section to the CAP wiki that becomes a directory of special handling and vendor specific parameters.  It will help prevent overlap between parameter values and useful values might eventually make it into the spec for the next CAP version.

For instance, a parameter I've been including is called "requestResponse" and its value is a URL or valid email address.  This allows feedback on who has received a message which is of key importance for Private scope messages with a list of addresses.  Works like a return receipt for email.

-- 
lists at jpw.biz
--