Next the packet's header information is compared with each rule in the chain it is passed on to, unless it perfectly matches a rule.
接下来，将信息包的头信息与它所传递到的链中的每条规则进行比较，看它是否与某条规则完全匹配。
Although there are cases where a remote application legitimately needs to set the message header fields, this is the exception rather than the rule.
虽然远程应用程序有时需要设置消息头部字段，但这只是例外情况，而不是规则。
Many frameworks in Objective-C provide a wrapper header that imports all the enclosed class headers; this could be provided quite easily by developing a package rule.
Objective - C中的很多框架都提供了一个包装头，它可以导入所有附着在上面的类头；这通过开发一个包规则可以很容易的提供。
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