Re: KEYDATA was Re: ipv6 was Re: LC model draft draft-ietf-forces-model-07.txt

Yes, this I understand.  I recommend you add something along these lines, but
might I suggest a slightly tighter wording?.

Tom Petch

----- Original Message -----
From: "Joel M. Halpern" <[email protected]>
To: <[email protected]>
Sent: Friday, October 27, 2006 5:20 PM
Subject: Re: KEYDATA was Re: ipv6 was Re: LC model draft
draft-ietf-forces-model-07.txt

> Then clearly we need better text.
>
> I will try here to provide an explanation, so that next time folks
> can check if the text better explains the goal.
>
> Arrays have indices.
<tp>I assume there is one array per index; then I find it clearer to say
"An array has a single index."
> Indices are always 32 bit integers. An array
> can have a fixed or variable number of entries.  For variable size
> arrays, there can be a declared maximum, and the FE may place a
> smaller maximum on the size.
> The path to an array element consists of the path to the array,
> followed by the subscript,
<tp>I take subscript to be a synonym of index or index value; in which case
I would prefer to stay with those words
> optionally followed by additional path if
> one is trying to get a more specific piece of the array element.

I then wonder who creates the index value, are they
consecutive integers, is the value for an array entry fixed for the life of the
array entry?

>
> In addition, there is content keying.

<tp> suggest
"The element of an array can also be accessed by content keying."

> This allows the CE to
> reference an element of the array by the value stored in the array
> rather than by the index.  Only elements which are declared to form a
> content key can be used as a content key.  Content keys must be
> unique in an array.
<tp>Again I can see an ambiguity; what I think this means is
"A content key can consist of several elements; a given set of values of those
elements must uniquely identify one element in the array."

> To reference an element by a content key, one uses a path, with an
> option indicating that there is a content key.  A TLV contains the
> content keying information.  There can be nested path-data TLVs to
> allow one to select elements from within the array element.
>
> So, content keying is an alternate way of selecting an array
> element.  Any field or combination of fields in the array element can
> be declared to be a content key, and can be used for a content key reference.
>
> Yours,
> Joel M. Halpern
>
> PS: I personally consider the entire content keying notion gratuitous
> and unnecessary complexity.  But the working group agreed that it was
> worth having, so I will do my best to explain it in the
> document.  But I don't have to like it.
>
<snip>