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 (Note:Command-Line Options.).
* The use of `CONVFMT' for controlling the conversion of numbers to
strings (Note:Conversion of Strings and Numbers.).
* The concept of a numeric string and tighter comparison rules to go
with it (Note:Variable Typing and Comparison Expressions.
).
* More complete documentation of many of the previously undocumented
features of the language.
The following common extensions are not permitted by the POSIX
standard:
* `\x' escape sequences are not recognized (Note:Escape
Sequences).
* Newlines do not act as whitespace to separate fields when `FS' is
equal to a single space (Note:Examining Fields.).
* Newlines are not allowed after `?' or `:' (Note:Conditional
Expressions.).
* The synonym `func' for the keyword `function' is not recognized
(Note:Function Definition Syntax.).
* The operators `**' and `**=' cannot be used in place of `^' and
`^=' (Note:Arithmetic Operators., and Note:Assignment Expressions.
* Specifying `-Ft' on the command line does not set the value of
`FS' to be a single tab character (Note:Specifying How Fields Are
Separated.).
* The `fflush' built-in function is not supported (Note:Input/Output Functions.).