Environment::extRelPath() 

\nn\t3::Environment()->extRelPath($extName = ''); 

relativen Pfad (vom aktuellen Script aus) zu einer Extension holen z.B. ../typo3conf/ext/nnsite/

\nn\t3::Environment()->extRelPath('extname');

| @return string

public function extRelPath ( $extName = '' ) {
	return PathUtility::getRelativePathTo( $this->extPath($extName) );
}