a comment on the fragment document

Apologies if this duplicates earlier discussion, I am behind on the 
e-mail traffic.

The main thing that I took from the WG telecon discussion of the 
fragments, which I don't find in the document is a very high level 
motivation:

This fragment is intended for X
This fragment is intended for Y

etc.

I suggest that could go in the introduction.

I realise that the complexity section justifies such statements, but 
feel that the intent that was fairly clear in the WG discussion should 
be clear to the casual reader (i.e. who reads the beginning and then 
gives up, because it gets too technical!) of this document.

Jeremy