A coding standard in PHP_CodeSniffer is a collection of sniff files. Each sniff file checks one part of the coding standard only. Multiple coding standards can be used within PHP_CodeSniffer so that the one installation can be used across multiple projects. The default coding standard used by PHP_CodeSniffer is the PEAR coding standard.
If you want to know more about PHP_CodeSniffer please visit http://pear.php.net/manual/en/package.php.php-codesniffer.intro.php