PER_LINUX,
    PER_SVR4,
    PER_SVR3,
    PER_SCOSVR3,
    PER_OSR5,
    PER_WYSEV386,
    PER_ISCR4,
    PER_BSD,
    PER_SUNOS,
    PER_XENIX,
    PER_LINUX32,
    PER_IRIX32,
    PER_IRIXN32,
    PER_IRIX64,
    PER_RISCOS,
    PER_SOLARIS,
    PER_UW7,
    PER_OSF4,
    PER_HPUX,
    PER_MASK,