[Model] Section 4.5.3

Continuing where i left off ...

- Glad to see you can have multiple keys as well as index at the same
time. I had totally forgotten where that long discussion ended.

- Everything that reads "attribute" in this section implies "property";
so that lingering lingo issue is still distracting.
[Example: 
"The array can be "fixed-size" or "variable-size", which is specified 
 by the "type" attribute of the <array> element. The default is 
 "variable-size".  For variable size arrays, an optional "max-length" 
 attribute specifies the maximum allowed length. This attribute 
 should be used to encode semantic limitations, not implementation 
 limitations. The latter should be handled by capability attributes .." 
]

- readability/flow
a) The paragraph that goes:
 " Each key is declared with a keyID for use in the protocol,"

and 
b) the example on ipPrefixInfo_table 
 
Should really be in section 4.5.3.1

BTW, that example uses ipv4Prefix reference which is given as an example
in 4.5.4. It would be useful to point to that example.

I would like to enter this in the tracker unless there is disagreement.
If i dont hear any disagreements, it will go in the tracker.

cheers,
jamal