public static function setConceptualModelRoles( $taxonomy = null )
	{
		$cmTaxonomy = $taxonomy ? $taxonomy->getTaxonomyForXSD("cm.xsd") : null;
		if ( $cmTaxonomy )
		{
			$nonDimensionalRoleRef = $cmTaxonomy->getNonDimensionalRoleRefs( XBRL_Constants::$defaultLinkRole );
			if ( isset( $nonDimensionalRoleRef[ XBRL_Constants::$defaultLinkRole ] ) )
			{
				$cmArcRoles = $nonDimensionalRoleRef[ XBRL_Constants::$defaultLinkRole ];
				self::$conceptualModelRoles = $cmArcRoles;

				return;
			}
		}

		// Fallback
		self::$conceptualModelRoles = self::$defaultConceptualModelRoles;
	}