GNU indent: what exactly -gnu is

gistfile1.txt

-gnu	- Use GNU coding style.  This is the default.
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-nbad	- Do not force blank lines after declarations.
-bap	- Force blank lines after procedure bodies.
-nbc	- Do not force newlines after commas in declarations.
-bbo	- Prefer to break long lines before boolean operators.
-bl	- Put braces on line after if, etc.
-bli2	- Indent braces 2 spaces.
-bls	- Put braces on the line after struct declaration lines.
-ncdb	- Do not put comment delimiters on blank lines.
-nce	- Do not cuddle } and else.
-cp1	- Put comments to the right of #else and #endif statements in column 1.
-cs	- Put a space after a cast operator.
-di2	- Put variables in column 2.
-ndj	- Comments after declarations are treated the same as comments after other statements.
-nfc1	- Do not format comments in the first column as normal.
-nfca	- Do not format any comments.
-hnl	- Prefer to break long lines at the position of newlines in the input.
-i2	- Set indentation level to 2 spaces.
-ip5	- Indent parameter types in old-style function definitions by 5 spaces.
-lp	- Line up continued lines at parentheses.
-pcs	- Insert a space between the name of the procedure being called and the ‘(’.
-nprs	- Do not put a space after every ’(’ and before every ’)’.
-psl	- Put the type of a procedure on the line before its name.
-saf	- Put a space after each for.
-sai	- Put a space after each if.
-saw	- Put a space after each while.
-nsc	- Do not put the ‘*’ character at the left of comments.
-nsob	- Do not swallow optional blank lines.