In databases,an operator,with detailed knowledge of the search methods and techniques,who conducts a search on behalf of an end user. 在数据库中，熟悉检索方法和检索技术的操作员，他替终端用户作检索。
The first one is the content-based image search, and the second is the layered content protection. 其一是基于影像内容的检索方法，另一个则是层次式内容保护方式。
