NAME
        EnqueueCxObj -- insert a commodity object within a list of objects
                        based on object priority. (V36)

   SYNOPSIS
        EnqueueCxObj(headObj,co);
                     A0      A1

        VOID EnqueueCxObj(CxObj *,cxobj *);

   FUNCTION
        This function puts object 'co' into the list of object 'headObj'.
        The insertion point is determined by the object's priority. The
        objects are kept in the list from the highest priority to the
        lowest. New nodes are inserted in front of the first node with a
        lower priority. Hence a FIFO queue for nodes of equal priority.

        The priority of the commodity object can be set using setcxobjpri().

   INPUTS
        headObj - pointer to a list of objects. If this value is NULL, then
                  the entire tree of objects pointed to by 'co' is deleted
                  and becomes invalid.
        co - the object to add to the list (may be NULL)

   RESULTS
        If 'co' is NULL, this function will record that fact in the
        internal accumulated error of 'headObj'. This error record
        can be retrieved using cxobjerror() and cleared using
        clearcxobjerror().

   BUGS
        Until V38, passing a NULL 'headObj' parameter would cause low-memory
        access and unpredictable results.

   SEE ALSO
        setcxobjpri(), cxobjerror(), clearcxobjerror()