SIGUSR1

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
  1. auto SIGUSR1;
  2. auto SIGUSR1;
  3. auto SIGUSR1;
  4. auto SIGUSR1;
    version(!linux && !OSX && !FreeBSD && solaris)
    extern (C) const
    auto SIGUSR1 = 16;

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