NAME
        InsertCxObj -- insert a commodity object in a list after a given
                       object. (V36)

   SYNOPSIS
        InsertCxObj(headObj,co,pred);
                    A0      A1 A2

        VOID InsertCxObj(CxObj *,cxobj *,cxobj *);

   FUNCTION
        Adds 'co' to the list of objects pointed to by 'headObj' after
        object 'pred'.

   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)
        pred - the object after which 'co' should be inserted. If this is NULL
               then 'co' is added to the head of the list.

   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
        cxobjerror(), clearcxobjerror()