A.3 Changes Between SVR4 and POSIX awk

The POSIX Command Language and Utilities standard for awk (1992) introduced the following changes into the language:

• The use of ‘-W’ for implementation-specific options (see section Command-Line Options).
• The use of CONVFMT for controlling the conversion of numbers to strings (see section Conversion of Strings and Numbers).
• The concept of a numeric string and tighter comparison rules to go with it (see section Variable Typing and Comparison Expressions).
• The use of built-in variables as function parameter names is forbidden (see section Function Definition Syntax.
• More complete documentation of many of the previously undocumented features of the language.

See section Common Extensions Summary, for a list of common extensions not permitted by the POSIX standard.

The 2008 POSIX standard can be found online at http://www.opengroup.org/onlinepubs/9699919799/.