Cancels all pending I/O requests on a specified channel. In
    general, this includes all I/O requests that are queued, as well
    as the request currently in progress.

    Format

      SYS$CANCEL  chan

    C Prototype

      int sys$cancel  (unsigned short int chan);

1  –  Argument

 chan

    OpenVMS usage:channel
    type:         word (unsigned)
    access:       read only
    mechanism:    by value
    I/O channel on which I/O is to be canceled. The chan argument is
    a word containing the channel number.