NAME
        ChangeMode - Change the current mode of a lock or filehandle (V36)

   SYNOPSIS
        success = ChangeMode(type, object, newmode)
        D0                    D1     D2      D3

        bool changemode(ulong, bptr, ulong)

   FUNCTION
        This allows you to attempt to change the mode in use by a lock or
        filehandle.  For example, you could attempt to turn a shared lock
        into an exclusive lock.  The handler may well reject this request.
        Warning: if you use the wrong type for the object, the system may
        crash.

   INPUTS
        type    - Either CHANGE_FH or CHANGE_LOCK
        object  - A lock or filehandle
        newmode - The new mode you want

   RESULT
        success - Boolean

   BUGS
        Did not work in 2.02 or before (V36).  Works in V37.  In the
        earlier versions, it can crash the machine.

   SEE ALSO
        lock(), open()