Clarification of what is a shape

shacl/index.html

@@ -779,7 +779,8 @@ <h3>Shapes</h3>
 				<p>
 					A <dfn data-lt="shape|shapes">shape</dfn> can be a <a>node</a> in a <a>shapes graph</a> that is
 					a <a>SHACL instance</a> of <code>sh:Shape</code>;
-					or it can be a node so that the <a>expected type</a> of the node is <code>sh:Shape</code>.
+					or it can be a node so that the <a>expected type</a> of the node is <code>sh:Shape</code>,
+					or a node that has a <a>value</a> for a <a>target</a> property such as <code>sh:targetClass</code> in the <a>shapes graph</a>.
 				</p>
 				<p>
 					A shape provides a set of zero or more <a>targets</a>, <a>filters</a>, <a>constraints</a> and <a>parameters</a> of <a>constraint components</a>