What can the first line of a filters file look like?
过滤规则文件的第一行表示什么？
Usually the first line of a filters file is simply [Adblock]. However, you might have noticed that recent versions of Adblock Plus sometimes put a different text instead. This is done when you have filters in your list that use advanced filter syntax only supported by newer versions of Adblock Plus but not original Adblock. One example would be:
(Adblock Plus 0.6.1.2 or higher required) [Adblock]
This is simply a comment. Adblock (and Adblock Plus for that reason) will ignore anything before the actual mark. The required Adblock Plus version is not enforced because Adblock Plus 0.6.1.2 didn't support it. However, if you use even newer filter syntax, you might get something like:
[Adblock Plus 0.7.1]
This type of header is supported starting with Adblock Plus 0.7.1. Older Adblock Plus versions and Adblock cannot open files starting with this header. As to the current versions, they will check the version number in the header and compare it with their own version number. If the file happens to require a newer Adblock Plus, the user will be given a message on import asking him to upgrade. Subscriptions will still load files meant for newer Adblock Plus versions but display a warning in the preferences dialog.
Finally, if you want to require Adblock Plus but don't want to specify the version number you can start the file with [Adblock Plus]. Of course this file will only be accepted by Adblock Plus 0.7.1 or higher again.
过滤规则文件的第一行通常都是 [Adblock]。但您可能发现在最近版本的 Adblock Plus 中过滤文件第一行有时显示为其他文字，这是由于您列表中部分过滤规则的语法只支持新版本 Adblock Plus 而不支持早期的 Adblock。例如：
(Adblock Plus 0.6.1.2 or higher required) [Adblock]
这里括号中的内容只是一个注释，Adblock 或 Adblock Plus 读取时会忽略实际标记之前的任何内容。由于 Adblock Plus 0.6.1.2 还不支持这种写法，因此这里 Adblock Plus 不会强制要求用户更新到新版本。然而，如果您使用更加新的过滤规则语法，则第一行有可能会变成：
[Adblock Plus 0.7.1]
上面这种写法是从 Adblock Plus 0.7.1 开始支持的，而之前版本的 Adblock Plus 以及 Adblock 则无法打开这种文件。Adblock Plus 会将文件第一行的版本号和扩展自身版本号进行比较，如果文件要求的版本号高于扩展当前版本号，则 Adblock Plus 会提示用户更新到新版本。对于过滤规则订阅，它仍会加载这个文件，但会在首选项对话框显示扩展更新提示。
最后，如果只想兼容 Adblock Plus 但不在乎其版本号，您可以将文件第一行修改为 [Adblock Plus]。当然这样的过滤规则文件只支持 Adblock Plus 0.7.1 及更高版本。