o  You must specify a VIRTUAL FIELD DATATYPE for a field  using  the
      COMPUTED BY DATATRIEVE clause.

   o  Only  VAX  DATATRIEVE  can  interpret  VIRTUAL   fields.    Other
      processors  either  ignore  their  presence  or refuse to process
      record descriptions containing them.

   o  You can use 8-bit characters in CDDL quoted strings.

   o  You cannot specify an INITIAL VALUE field attribute for a virtual
      field.

   o  You cannot specify a CONDITION NAME field attribute for a virtual
      field.

   o  You cannot use a virtual field as a tag variable in the  VARIANTS
      OF field description statement.