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SET, ROOT, Description
 *Conan The Librarian 

    In POSIX pathname processing mode, RMS and the C Run-Time Library
    treat the leading slash (/) of a pathname as referring to the
    defined root. By default, the root is SYS$SYSDEVICE:[PSX$ROOT].
    The root definition does not persist across a reboot. The SET
    ROOT commands requires SYSNAM privilege and has the following
    qualifier:
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