| PER_LINUX 0 |
| PER_LINUX_32BIT ADDR_LIMIT_32BIT |
| PER_LINUX_FDPIC FDPIC_FUNCPTRS |
| PER_SVR4 (0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO) |
| PER_SVR3 (0x0002 | STICKY_TIMEOUTS | SHORT_INODE) |
| PER_SCOSVR3 (0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE) |
| PER_OSR5 (0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS) |
| PER_WYSEV386 (0x0004 | STICKY_TIMEOUTS | SHORT_INODE) |
| PER_ISCR4 (0x0005 | STICKY_TIMEOUTS) |
| PER_BSD 0x0006 |
| PER_SUNOS (0x0006 | STICKY_TIMEOUTS) |
| PER_XENIX (0x0007 | STICKY_TIMEOUTS | SHORT_INODE) |
| PER_LINUX32 0x0008 |
| PER_LINUX32_3GB (0x0008 | ADDR_LIMIT_3GB) |
| PER_IRIX32 (0x0009 | STICKY_TIMEOUTS) |
| PER_IRIXN32 (0x000a | STICKY_TIMEOUTS) |
| PER_IRIX64 (0x000b | STICKY_TIMEOUTS) |
| PER_RISCOS 0x000c |
| PER_SOLARIS (0x000d | STICKY_TIMEOUTS) |
| PER_UW7 (0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO) |
| PER_OSF4 0x000f |
| PER_HPUX 0x0010 |
| PER_MASK 0x00ff |
