The Erase Virtual Display routine erases all or part of a virtual
    display by replacing text characters with blanks.

    Format

      SMG$ERASE_DISPLAY  display-id [,start-row] [,start-column]

                         [,end-row] [,end-column]

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

    Specifies the virtual display to be erased. The display-id
    argument is the address of an unsigned longword that contains
    the display identifier.

    The display identifier is returned by SMG$CREATE_VIRTUAL_DISPLAY.

 start-row

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

    Specifies the row at which the erase operation begins. The start-
    row argument is the address of a signed longword that contains
    the number of the row at which the erasure begins.

    If the start-row argument is not specified, start-column is also
    ignored and the entire virtual display is erased. If you do not
    specify start-row and start-column, then end-row and end-column
    are ignored and the entire virtual display is erased.

 start-column

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

    Specifies the column at which the erase operation begins. The
    start-column argument is the address of a signed longword that
    contains the number of the column at which the erasure begins.

    If the start-column argument is not specified, start-row is also
    ignored and the entire virtual display is erased. If you do not
    specify start-row and start-column, then end-row and end-column
    are ignored and the entire virtual display is erased.

 end-row

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

    Specifies the row at which the erase operation ends; that is, the
    last row to be erased. The end-row argument is the address of a
    signed longword that contains the number of the last row to be
    erased.

    If the end-row argument is not specified, end-column is also
    ignored and all remaining rows in the display are erased.

 end-column

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

    Specifies the column at which the erase operation ends; that
    is, the last column to be erased. The end-column argument is the
    address of a signed longword that contains the number of the last
    column to be erased.

    If the end-column argument is not specified, end-row is also
    ignored and all remaining columns in the display are erased.