A custom tag library is comprised of one or more java language classes called tag handlers and an xml tag library description file , which dictates the new tag names and valid attributes for those tags 定制标记库由一个或多个java语言类（称为标记处理程序）以及xml标记库描述文件（ tld ）组成，后者描述新的标记名和那些标记的有效属性。
