The Create a Virtual Viewport routine creates a viewport and
    associates it with a virtual display. The location and size of
    the viewport are specified by the caller.

    Format

      SMG$CREATE_VIEWPORT  display-id ,viewport-row-start

                           ,viewport-column-start

                           ,viewport-number-rows

                           ,viewport-number-columns

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 display-id

    OpenVMS usage:identifier
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Display identifier of the virtual display associated with the
    newly created viewport. The display-id argument is the address of
    an unsigned longword containing this identifier.

 viewport-row-start

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Row number in the virtual display that will become row 1 in the
    viewport. The viewport-row-start argument is the address of a
    signed longword containing the row number.

 viewport-column-start

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Column number in the virtual display that will become column 1 in
    the viewport. The viewport-column-start argument is the address
    of a signed longword containing the column number.

 viewport-number-rows

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Number of rows in the viewport. The viewport-number-rows argument
    is the address of a signed longword containing the number of rows
    in the newly created viewport.

 viewport-number-columns

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Number of columns in the viewport. The viewport-number-columns
    argument is the address of a signed longword containing the
    number of columns in the newly created viewport.