Linux Standard Base
- The goal of the Linux Standard Base (LSB) is to develop and promote a set of standards that will increase compatibility among Linux distributions and enable software applications to run on any compliant Linux system.
- http://www.linux-foundation.org/en/LSB

UNIX System Interface Tables
- These pages contain tables of all the Commands and System interfaces defined in UNIX 98, complete with an indication of their availability in UNIX 95, the ISO POSIX-1 standard, the ISO POSIX-2 standard, the ISO C standard, SVID3 and 4.3BSD.
- http://www.unix-systems.org/apis.html