[sipcore] draft-barnes-sipcore-rfc4244bis - privacy syntax

["Dale Worley" <[e-mail]>]

I'm curious why the privacy attribute of an hi-targeted-to-uri is
specified by adding a header-parameter to the URI, rather than being
given as a field-parameter.  That is, an example of the current syntax
is:

  <sip:[e-mail]?Privacy=history&Reason=SIP%3Bcause%3D486>;index=1.2;mapped

where I would expect:

  <sip:[e-mail]?Reason=SIP%3Bcause%3D486>;index=1.2;mapped;privacy=history

This privacy value is an annotation of the URI, whereas the current
syntax incorporates it *into* the URI.  And indeed, to reconstitute the
actual historical request-URI, one has to remove the Privacy header from
the URI part of the name-addr, that is, the stuff inside <...>.
(Although given that the historical URI can have had no header
parameters (due its use as a request-URI), that processing step is not
ambiguous.)

In addition, the values of the 4244 Privacy header do not have exactly
the same semantics as the same tokens used as values of the Privacy
header.

I guess that for compatibility with RFC 4244, we have to continue to
record privacy and reason information in the URI this way, but I'm
curious what the motivation was for this rather unusual way to represent
this information.

Dale