private function _checkMandatoryHeader() {
		if ($this->_isActive('mandatoryHeader')) {

			$expectedHeader = $this->_config->getTestProperty('mandatoryHeader', 'header');
			$expectedHeader = trim($expectedHeader);
			$expectedHeader = preg_replace('~[\r\n\t ]+~', '', $expectedHeader);

			$filecontent = $this->tokenizer->content;
			$filecontent = preg_replace('~[\r\n\t ]+~', '', $filecontent);

			if (strpos($filecontent, $expectedHeader) === FALSE) {
				$this->_writeError('mandatoryHeader', $this->_getMessage('MANDATORY_HEADER'));
			}
		}
	}