C1004   Ambiguous variable reference, assuming memvar

     Explanation:  You made a reference to an undeclared or unaliased
     variable when compiling with the /W option, but the context of the
     program indicated that a MEMVAR declaration could be assumed.  This
     warning usually follows a "C1003 Ambiguous variable reference" warning
     message.

     Action:  In general, declare all variables used in a procedure or
     function.  If the variable is a database field, specify the variable
     prefaced by the work area or FIELD -> alias, or declare it within a
     FIELD statement.