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
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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
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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。
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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。