Good morning,

I have a question regarding the ABNF of the "header" component of a
SIP/SIP-URI as defined in RFC 3261, page 223. It seems from the rule that it
is possible for a header to not have a value (more precisely, to have a
value of length 0, as there is no numeric value preceding the asterisk in
the rule for "hvalue" - RFC 2234 states 0 as the default value in this
case). However, the rule for "header" states that the "=" character is not
optional which would make a construct like "someheader=" possible (which is
rather unusual in my eyes).
Is my interpretation of the ABNF correct in this case and a SIP parser must
accept a header without a value while still checking for the "=" or did they
just forgot the "1" in the "hvalue" rule and a header must always have a
nonzero-length value (or did they forgot about square brackets around " "="
hvalue") ? Or is it still too early and I'm unable to read ABNF this
morning? :D

Thanks in advance and best regards,

Peter
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