sparql update review

SPARQL-UPDATE review

In general I found this document very comprehensible and understandable and
I only have minor comment only about the presentation of the methods. In
the beginning I found it messy with starting with non informative sections
with examples and next with the informative ones. Section 3.1.3 contains
two informative subsections with the same title than the two sections
before (INSERT and DELETE informative sections), and I was a bit confused.
The purpose of clarifying what INSERT/DELETE does is clear with the
informative subsections, but maybe another naming could be used.

Another thing I found a bit difficult to understand is the definition of
QuadTriple and QuadData. QuadTriple is defined at the beginning of the
document in the terminology section, but QuadData is defined in Section
3.1.1. I would add a comment to diferentiate them clearly (looking at the
grammar have the same form). I would also add the formal definition of
QuadPattern to the formal model section.

Apart from these comments I found what I believe are two typos:

 - In example 6 all records with date before year 2000 are deleted but the
filter contains year 1970
 - In de dataset-UNION definition, iri_j is used but before it is defined
iri'_j

cheers,

Carlos