port-name

       Is the name of the port. It cannot duplicate a DEC DATATRIEVE
       keyword or the given name of any domain you may bring into your
       workspace.

    level-number

       Is the level number for the field in the port declaration. It
       indicates the relationship of the field to the other fields of
       the port.

    field-definition

       Is a field definition. A port declaration must have at least one
       field definition. Each field definition ends with a period.

    ; (semicolon)

       Ends the port declaration.