The Compaq C RTL implements parts of the following standards: o X/Open CAE Specification, System Interfaces and Headers, Issue 4, Version 2, also known as XPG4 V2. o X/Open CAE Specification, System Interfaces and Headers, Issue 4, also known as XPG4. o Standard for Information Technology - Portable Operating System Interface (POSIX) - Part 1: System Application Program Interface (API)-Amendment 2: Threads Extension [C Language], also known as POSIX 1003.1c-1995 or IEEE 1003.1c-1995. o ISO/IEC 9945-2:1993 - Information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities, also known as ISO POSIX-2. o ISO/IEC 9945-1:1990 - Information Technology - Portable Operating System Interface (POSIX) - Part 1: System Application Programming Interface (API) (C Language), also known as ISO POSIX-1. o ANSI/ISO/IEC 9899:1999 - The C99 standard, published by ISO in December, 1999 and adopted as an ANSI standard in April, 2000. o ISO/IEC 9899:1990-1994 - Programming Languages - C, Amendment 1: Integrity, also known as ISO C, Amendment 1. o ISO/IEC 9899:1990 - Programming Languages - C, also known as ISO C. The normative part is the same as X3.159-1989, American National Standard for Information Systems - Programming Language C, also known as ANSI C.