public static function generateSubattributeFieldName( eZContentClassAttribute $classAttribute, $subfieldName, $type )
    {
        // base name of subfields ends with self::SUBATTR_FIELD_PREFIX so
        // that it's possible to differentiate those fields in schema.xml
        $documentFieldName = self::getDocumentFieldName();

        return $documentFieldName->lookupSchemaName( self::SUBATTR_FIELD_PREFIX . $classAttribute->attribute( 'identifier' )
                                                            . self::SUBATTR_FIELD_SEPARATOR . $subfieldName . self::SUBATTR_FIELD_SEPARATOR,
                                                           $type );
    }