RE : : Using DIAMETER_MISSING_AVP for optional AVP

> From 3588:
> 
>    DIAMETER_MISSING_AVP               5005
>       The request did not contain an AVP that is required by the
Command
>       Code definition.  If this value is sent in the Result-Code AVP,
a
>       Failed-AVP AVP SHOULD be included in the message.  The
Failed-AVP
>       AVP MUST contain an example of the missing AVP complete with the
>       Vendor-Id if applicable.  The value field of the missing AVP
>       should be of correct minimum length and contain zeroes.
> 
> My guess is that if a particular implementation or 
> application was expecting an AVP to be included, this would 
> be a reasonable way to do it.
> 

Based on this definition, it is only applicable to AVP "required by the
command code definition". It is not clear if we could reuse the same
result code for an optional AVP.
If there is a general consensus on this topic, maybe a modification to
the existing definition should be done.

Besides, if we could reuse the same result code for required or optional
AVP, should we state that "a Failed-AVP AVP MUST be included" instead of
"should be included"?
My assumption was that a "SHOULD" was possible here because you could
have relyed on the command code ABNF descritpion to find the missing
AVP. If the above assupmtion is correct, it is not possible anymore and
you have to use the Failed-AVP.

Lionel