The following example assigns a missing  value  of  0  to  the  field
  PRICE.   A  PRICE of 0 indicates to VAX DATATRIEVE that the value for
  PRICE is missing; VAX DATATRIEVE ignores records with PRICE equal  to
  0 when it performs operations involving the PRICE field.

  PRICE                       DATATYPE IS UNSIGNED NUMERIC
                              SIZE IS 8 DIGITS 2 FRACTIONS
                              MISSING_VALUE FOR DATATRIEVE IS 0.