--- a/rdf-mt/index.html	Mon Apr 15 17:10:18 2013 +0100
+++ b/rdf-mt/index.html	Tue Apr 30 07:57:50 2013 -0700
@@ -125,7 +125,7 @@
  <section>
       <h2 id="notation">Notation and terminology</h2>
 
-<p class="issue">This section needs cleaning up. Some of the 2004 definitions may no longer be needed. The notions of instance and equivalence may (?) need to be stated more carefully taking bnode scopes into account. Instance mappings should be defined on a whole scope rather than a graph (?). The definitions involving bnode scopes and complete graphs are new. <br/><br/> Maybe some of the material should be in Concepts. </p>
+<p class="issue">This section needs some cleaning up. Some of the 2004 definitions may no longer be needed. <br/><br/> Maybe some of the material should be in Concepts. </p>
 
       <p>This document uses the terminology //list terms// defined in //Concepts// for describing RDF graph syntax.</p>
 
@@ -196,9 +196,15 @@
   to be <dfn>equivalent</dfn>.  Equivalent graphs are mutual instances with an invertible instance 
   mapping. As blank nodes have no particular identity beyond their location in a graph, we will often treat such equivalent graphs as identical.</p>
 
-<p>Any set of graphs can be treated as a single graph simply by taking the union of the sets of triples. If two or more of the graphs share a blank node it will retain its identity when the union graph is formed. Graphs can share blank nodes only if they are derived from graphs described by documents or surface structures which share a single scope for blank node identifiers.</p>
-<p class="issue">The Concepts document does not yet define blank node identifier scopes.</p>
-
+<p>
+Graphs share blank nodes only if they are derived from graphs
+described by documents or other structures (such as the data
+structures in an RDF store) that explicitly provide for the sharing
+of blank nodes between different RDF graphs.  Simply downloading a
+web document does not mean that the blank nodes in a resulting RDF
+graph are the same as the blank nodes coming from other downloads of
+the same document.
+</p>
 
 <p>We will refer to this process of forming the union of graphs as <dfn>merging</dfn>, and to the union graph as the <dfn>merge</dfn> of the original graphs. A merge may be represented by a new document or datastructure, or may be treated as a conceptual entity when processing RDF.</p>
 
@@ -319,12 +325,16 @@
         </tbody>
       </table>
 
-<p>Mappings from blank nodes to referents are not part of the definition of an interpretation, since the truth condition refers only to <em>some</em> such mapping. Blank nodes themselves differ from other nodes in not being assigned a denotation by an interpretation, reflecting the intuition that they have no 'global' meaning outside the scope in which they occur.</p>
+<p>Mappings from blank nodes to referents are not part of the definition of an interpretation, since the truth condition refers only to <em>some</em> such mapping. 
+Blank nodes themselves differ from other nodes in not being assigned
+a denotation by an interpretation, reflecting the intuition that
+they have no 'global' meaning.
+</p>
 
 <h3 id="intuitions">Intuitive summary</h3>
 
 <p>An RDF graph is true exactly when:</p>
-<p>1. the IRIs and literals in subject or object position in the graph all refer to things,</p><p>2. there is some way to interpret all the blank nodes in the scope as referring to things,</p><p>3. the IRIs in property position identify binary relationships,</p><p>4. and, under these interpretations, each triple S P O in the graph asserts that the thing referred to as S, and the thing referred to as O, do in fact stand in the relationship identified by P. </p>
+<p>1. the IRIs and literals in subject or object position in the graph all refer to things,</p><p>2. there is some way to interpret all the blank nodes in the graph as referring to things,</p><p>3. the IRIs in property position identify binary relationships,</p><p>4. and, under these interpretations, each triple S P O in the graph asserts that the thing referred to as S, and the thing referred to as O, do in fact stand in the relationship identified by P. </p>
 
 <p>All semantic extensions of any vocabulary or higher-level notation encoded in RDF MUST conform to these minimal truth conditions. Other semantic extensions may extend and add to these, but they MUST NOT over-ride or negate them. </p>