Fill in the notation information about the schema element

descriptions.

doc/ZConfig/zconfig.tex

@@ -272,7 +272,12 @@ schema.
 
 \subsection{Schema Elements \label{elements}}
 
-XXX need to discuss notation
+For each element, the content model is shown, followed by a
+description of how the element is used, and then a list of the
+available attributes.  For each attribute, the type of the value is
+given as either the name of a \module{ZConfig} datatype or an XML
+attribute value type.  Familiarity with XML's Document Type Definition
+language is helpful.
 
 The following elements are used to describe a schema: