org\parser\driver\Markdown::doHorizontalRules PHP Method

    protected function doHorizontalRules($text)
    {
        # Do Horizontal Rules:
        return preg_replace('{
				^[ ]{0,3}	# Leading space
				([-*_])		# $1: First marker
				(?>			# Repeated marker group
					[ ]{0,2}	# Zero, one, or two spaces.
					\\1			# Marker character
				){2,}		# Group repeated at least twice
				[ ]*		# Tailing spaces
				$			# End of line.
			}mx', "\n" . $this->hashBlock("<hr{$this->empty_element_suffix}") . "\n", $text);
    }