public function validateLegalAttributes( $node )
	{
		if ( ! XBRL::isValidating() ) return true;

		// Tuple elements should not have attributes from XBRL namespaces
		$illegalAttributes = array();
		foreach ( XBRL_Constants::$standardPrefixes as $prefix => $namespace )
		{
			if ( $prefix == STANDARD_PREFIX_SCHEMA ) continue;
			if ( $prefix == STANDARD_PREFIX_SCHEMA_INSTANCE ) continue;

			foreach ( $node->attributes( $namespace ) as $key => $attribute )
			{
				$illegalAttributes[] = $prefix . ":" . $attribute->getName();
			}
		}

		if ( $illegalAttributes )
		{
			$this->log()->taxonomy_validation( "4.9", "Attributes assigned to tuples should not be ones defined in XBRL specification namespaces",
				array(
					'name' => $node->getName(),
					'attributes' => "'" . join( ', ', $illegalAttributes ) . "'",
				)
			);

			return true;
		}

		return false;
	}