TRANOTDIF, Transformation numbers are not dif-
        ferent (ERR=260)
        Explanation: The same transformation number is used
        twice in the SET INPUT PRIORITY statement.
        User Action: Specify two different transformations in
        the SET INPUT PRIORITY statement.

  UNEFILDAT, unexpired file date (ERR=179)
        Explanation: The program attempts to delete a file
        whose expiration date has not yet passed.
        User Action: None.

  UNINUMNOT, Unit number is not defined for the
        device (ERR=282)
        Explanation: The specified unit is a method that is not
        supported by the device. (The default unit is 1.)
        User Action: Verify the supported units for the device
        and specify a valid unit.

  UNKGKSERR, Unknown DEC GKS FOR VMS error
        (ERR=286)
        Explanation: A graphics error has occurred that is not
        mapped to a BASIC error message.
        User Action: Use VMSSTATUS to access the text of the
        DEC GKS error message.

  USEABOINP, User aborted input, locate point can-
        celled (ERR=293)
        Explanation: ERROR - The middle mouse button was
        pressed during the execution of a graphics input state-
        ment that uses a mouse to enter points (for example,
        LOCATE POINT). The pressing of the middle mouse
        button aborts the graphics input statement in progress
        and the data in the variables used for the graphics input
        statement is unchanged.
        The pressing of the middle mouse button during a graph-
        ics input statement is analogous to typing Ctrl/Z at a
        regular INPUT statement.
        User Action: None. The program can trap this error in
        an error handler and attempt the input statement again
        if so desired.

  VIRARRDIS, Virtual array not on disk (ERR=43)
        Explanation: The program attempted to reference a
        virtual array on a nondisk device, or the virtual array is
        not opened as ORGANIZATION VIRTUAL.
        User Action: Virtual arrays must be on disk; change the
        file specification in the OPEN statement for this array.
        Open the file with ORGANIZATION VIRTUAL.

  VIRARROPE, Virtual array not yet open (ERR=45)
        Explanation: The program attempted to reference a
        virtual array before opening the associated disk file.
        User Action: Open the disk file containing the virtual
        array before referencing the array.

  VIRBUFTOO, Virtual buffer too large (ERR=42)
        Explanation: The program attempted to access a
        VIRTUAL file and the buffer size was not 512 bytes.
        User Action: Change the I/O buffer to be a multiple of
        512 bytes.