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diff --git a/src/org/z3950/zing/cql/CQLNode.java b/src/org/z3950/zing/cql/CQLNode.java
index 10bd282..eab6db4 100644
--- a/src/org/z3950/zing/cql/CQLNode.java
+++ b/src/org/z3950/zing/cql/CQLNode.java
@@ -1,33 +1,80 @@
-// $Id: CQLNode.java,v 1.2 2002-10-25 16:01:26 mike Exp $
+// $Id: CQLNode.java,v 1.12 2002-11-06 20:13:45 mike Exp $
 
 package org.z3950.zing.cql;
+import java.util.Properties;
 
 
 /**
- * Represents a node in a CQL parse-tree ...
- * ###
+ * Represents a node in a CQL parse-tree.
  *
- * @version	$Id: CQLNode.java,v 1.2 2002-10-25 16:01:26 mike Exp $
+ * @version	$Id: CQLNode.java,v 1.12 2002-11-06 20:13:45 mike Exp $
  */
 public abstract class CQLNode {
-    abstract String toXCQL(int level);
-    abstract String toCQL();
-
-    protected String indent(int level) {
-	String x = "";
-	while (level-- > 0) {
-	    x += "  ";
-	}
-	return x;
-    }
-
-    /*
-    // Test harness
-    public static void main (String[] args) {
-	CQLNode n1 = new CQLTermNode("dc.author", "=", "kernighan");
-	CQLNode n2 = new CQLTermNode("dc.title", "all", "elements style");
-	CQLNode root = new CQLAndNode(n1, n2);
-	System.out.println(root.toXCQL(3));
-    }
-    */
+    CQLNode() {}		// prevent javadoc from documenting this
+
+    /**
+     * Translates a parse-tree into an XCQL document.
+     * <P>
+     * @param level
+     *	The number of levels to indent the top element of the XCQL
+     *	document.  This will typically be 0 when invoked by an
+     *	application; it takes higher values when this method is
+     *	invoked recursively for nodes further down the tree.
+     * @return
+     *	A String containing an XCQL document equivalent to the
+     *	parse-tree whose root is this node.
+     */
+    abstract public String toXCQL(int level);
+
+    /**
+     * Decompiles a parse-tree into a CQL query.
+     * <P>
+     * @return
+     *	A String containing a CQL query equivalent to the parse-tree
+     *	whose root is this node, so that compiling that query will
+     *	yield an identical tree.
+     */
+    abstract public String toCQL();
+
+    /**
+     * Renders a parse-tree into a Yaz-style PQF string.
+     * <P>
+     * <PRE>
+	query ::= top-set query-struct.
+	top-set ::= [ '@attrset' string ]
+	query-struct ::= attr-spec | simple | complex | '@term' term-type
+	attr-spec ::= '@attr' [ string ] string query-struct
+	complex ::= operator query-struct query-struct.
+	operator ::= '@and' | '@or' | '@not' | '@prox' proximity.
+	simple ::= result-set | term.
+	result-set ::= '@set' string.
+	term ::= string.
+	proximity ::= exclusion distance ordered relation which-code unit-code.
+	exclusion ::= '1' | '0' | 'void'.
+	distance ::= integer.
+	ordered ::= '1' | '0'.
+	relation ::= integer.
+	which-code ::= 'known' | 'private' | integer.
+	unit-code ::= integer.
+	term-type ::= 'general' | 'numeric' | 'string' | 'oid' | 'datetime' | 'null'.
+     * </PRE>
+     * @return
+     *	A String containing a PQF query equivalent to the parse-tree
+     *	whose root is this node.  This may be fed into the tool of
+     *	your choice to obtain a BER-encoded packet.
+     */
+    abstract public String toPQF(Properties config)
+	throws PQFTranslationException;
+
+    /**
+     * Returns a String of spaces for indenting to the specified level.
+     */
+    protected static String indent(int level) { return Utils.indent(level); }
+
+    /**
+     * Returns the argument String quoted for XML.
+     * For example, each occurrence of <TT>&lt;</TT> is translated to
+     * <TT>&amp;lt;</TT>.
+     */
+    protected static String xq(String str) { return Utils.xq(str); }
 }