Subject: Re: [MMUSIC] Review of draft-ietf-mmusic-rid-07

From: Adam Roach <[email-masked]>
Date: Tue, 25 Oct 2016 16:51:18 -0500

Thanks for the comments!

On 9/1/16 17:01, Peter Thatcher wrote:
> 1.  The things added to an a=rid line are typically called 
> "restrictions" and "constraints".  But in one place they are called 
> "characteristics". Further, one of the "constraints" is "depend", 
> which isn't a restriction at all, and more like a characteristic.  So 
> which is it?   I think that it would make sense to call them generally 
> "characteristics" (or a similar word, like "properties") and say that 
> the most common use of these "characteristics" is "restrictions" or 
> "constraints".

These are two different concepts. Codec properties (which I'd called 
"characteristics" in a couple places, but changed to "properties" to be 
consistent) refer to a specific value that a codec has, while 
"restrictions" (which I'd called "constraints" in a few places, but 
changed to "restrictions" to be consistent) describes the value(s) that 
these property are allowed to assume.

You can think of it this way: a volume knob may be restricted to the 
range zero through five, but have the property of being set to three.

> 2.  Sometimes the text says "constrain" and "constraint", other times 
> "restrict" and "restriction".  Can we just pick one and use it 
> consistently?  I've "a=rid" is a "restriction identifier", then I'd 
> suggest we go with restrict/restriction, but I'd be fine either way.  
> As long as we're consistent around one set of words.

I've removed "constraint" completely (Bernard raises a good point that 
this is a terminology collision with W3C WebRTC specs) in favor of 
"restriction."

> 3.  There are a bunch of rules that end up saying to remove/discard a 
> line. Sometimes the text says to remove, sometimes to discard, and 
> sometimes even "discard and not include".  Can we pick one and be 
> consistent?  I'd prefer "discard and not include", or maybe just 
> "discard", both of which are more clear to me than "remove".

Sure, I've changed them all to "discard."

> 4.  There is a phrase which says "If the offerer wishes the answerer 
> to have the ability to specify a constraint, but does not wish to set 
> a value itself, it MUST ...".  Is it normal to write MUST sentence in 
> the form "if you want X, you MUST do Y?"  Isn't it more correct to say 
> "if you want X, you MAY do Y"?  It's the answerer of the empty 
> constraint that MUST interpret it a certain way, but there's no reason 
> that the offerer MUST set the empty constraint.  That's just one thing 
> it may choose to do.

I've just removed the normative term here, since I don't think it adds 
any clarity. The formulation is now: "If you want X, you do Y."

/a