--- a/rdf-concepts/index.html	Wed Apr 25 17:00:33 2012 -0700
+++ b/rdf-concepts/index.html	Thu Apr 26 18:19:24 2012 +0100
@@ -1012,7 +1012,7 @@
     <a title="literal value">values of literals</a> is usually
     more helpful than comparing their syntactic forms
     (<a>literal equality</a>).
-    Similarly, for comparing <a title="RDF graph">RDF Graphs</a>,
+    Similarly, for comparing <a title="RDF graph">RDF graphs</a>,
     semantic notions of <a>entailment</a> are usually more helpful
     than syntactic <a>graph equivalence</a>.</p>
 
@@ -1037,7 +1037,7 @@
 
     <ul>
     <li>Exactly one <dfn>default graph</dfn>, being an <a>RDF graph</a>.
-    The default graph does not have a name.</li>
+    The default graph does not have a name and MAY be empty.</li>
     <li>Zero or more <dfn title="named graph">named graphs</dfn>.
     Each named graph is a pair consisting of an <a>IRI</a>
     (the <dfn>graph name</dfn>), and an <a>RDF graph</a>.
@@ -1076,7 +1076,7 @@
         <p>The design presented here should be considered a straw man proposal at this point. It is based on RDF Datasets as <a href="http://www.w3.org/TR/sparql11-query/#rdfDataset">defined in SPARQL 1.1</a>.</p>
     </div>
 
-    <p class="note">When graphs are merged, their blank nodes must be kept
+    <p class="note">When RDF graphs are merged, their blank nodes must be kept
     distinct if meaning is to be preserved; this may call for re-allocation of
     blank node identifiers.</p>
     </div>