/sys$common/syshlp/helplib.hlb
CRTL, msync, Arguments
 *Conan The Librarian 

 addr

    The address of the region that you want to synchronize.

 len

    The length, in bytes, of the region that you want to synchronize.

 flags

    One of the following symbolic constants defined in the <mman.h>
    header file:

    MS_SYNC        Synchronous cache flush
    MS_ASYNC       Asynchronous cache flush
    MS_            Invalidate cashed pages
    INVALIDATE
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