[Slim] Collapse attribute syntax to one line in draft-ietf-slim-negotiating-human-language

[Randall Gellens <[e-mail]>]

In response to Adam Roach's comments as well as other comments, I 
intend to update the draft to collapse the attribute syntax to one 
line; each attribute can occur at most once per media, with all 
languages on the same line.  This will further reduce the size of the 
SDP block.

If you object to this, please reply.

Here is the section of Adam's review:

At 8:31 PM +0000 3/28/17, Sabrina Tanamal via RT wrote:
>  I'll note that much of this can be fixed if the syntax is collapsed so
>  that each media section can have at most one hlang-send and one
>  hlang-receive, each of which contain a list of one or more languages
>  that can be sent or received. This is also much more consistent with the
>  way SDP attributes are used in general. The presence of a "*" token on
>  that line would indicate the "call should happen even without matching
>  languages" characteristic; since there is only one place to add this
>  indicator, the ambiguity of some lines indicating it and others not
>  disappears. The preceding example would collapse to:
>
>  m=audio 49250 RTP/AVP 20
>  a=hlang-send:es eu en *
>  a=hlang-recv:es eu en *
>
>  ...and the example text would be revised to remove the implication that
>  *sending* "es" necessarily implies *receiving* "es".
>
>  I'll further note that the majority of SDP libraries I've worked with
>  would make accessing the all-on-one-line format easier than
>  one-line-per-language as well.

Here is the proposed ABNF:

    Attribute Syntax:

       hlang-value =  Language-Tag *( SP Language-tag ) [ SP asterisk ]

                            ; Language-Tag as defined in BCP 47

       asterisk    =  "*"   ; an asterisk (ASCII %2A) character

       sp          =  1*" " ; one or more ASCII space (%20) characters

-- 
Randall Gellens
Opinions are personal;    facts are suspect;    I speak for myself only
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