```--- a/src/include/compiler/NodeFactory.h
+++ b/src/include/compiler/NodeFactory.h
@@ -6,18 +6,64 @@

namespace jags {

-class Node;
+    class Node;

-inline bool lt(double value1, double value2)
-{
-    return value1 < value2 - 16 * DBL_EPSILON;
-}
+    /**
+     * @short Fuzzy less than function for doubles
+     *
+     * Gives an ordering for doubles allowing for some numerical
+     * tolerance.  Values that are "nearly equal" are considered to be
+     * equal.
+     */
+    inline bool lt(double value1, double value2)
+    {
+	return value1 < value2 - 16 * DBL_EPSILON;
+    }
+
+    /**
+     * @short Fuzzy less than function for arrays of doubles
+     *
+     * Gives an ordering for two arrays of doubles of the same length.
+     * Values that are numerically "nearly equal" are considered to
+     * be equal.
+     */
+    bool lt(double const *value1, double const *value2, unsigned int length);

-bool lt(std::vector<double> const &value1, std::vector<double> const &value2);
-bool lt(double const *value1, double const *value2, unsigned int length);
-//bool lt(Node const *node1, Node const *node2);
-bool lt(std::vector<Node const *> const &par1,
-	std::vector<Node const *> const &par2);
+    /**
+     * @short Fuzzy less than function for Nodes
+     *
+     * Gives an ordering for Nodes that is arbitrary, but reproducible
+     * within the same process. This is all that is required by the
+     * various Node factories.
+     *
+     * In this ordering fixed nodes come before non-fixed nodes. Fixed
+     * nodes are ordered within themselves using the fuzzy less than
+     * operator for their values. Non-fixed nodes are sorted by their
+     * pointer values (which gives an arbitrary, but strict ordering).
+     */
+    bool lt(Node const *node1, Node const *node2);
+
+    /**
+     * @short Fuzzy less than function for vectors of Nodes
+     *
+     * Extends the fuzzy less than operator for Nodes to vectors of
+     * Nodes. Vectors are first sorted by length, then an element-wise
+     * comparison of each Node in the vector.
+     */
+    bool lt(std::vector<Node const *> const &par1,
+	    std::vector<Node const *> const &par2);
+
+
+    /**
+     * Template that constructs a function object from any of the
+     * above less than functions.
+     */
+    template<typename T> struct fuzzy_less
+    {
+	bool operator()(T const &arg1, T const &arg2) const {
+	    return lt(arg1, arg2);
+	}
+    };

} /* namespace jags */

```