Objects for each part of the header control 包含为标头控件的每个部件提供
2.
Objects for each state of an item of the header control 为标头控件的项的每种状态提供
3.
Objects for each state of the leftmost item of the header control 为标头控件最左端的项的每种状态提供
4.
Http header controls how documents are to be cached on the network Http标头控制在网络上缓存文档的方式。
5.
Sets the cache - control http header . the cache - control http header controls how documents are to be cached on the network [本主题是预发布的文档，在将来发布的版本中可能会有更改。空白主题是为将来预留的。
