What does _ah mean in Google App Engine?

Does the _ah mean anything in Google App Engine?

I'm not looking to find out what it's used for or where is it located and how it works. As s开发者_如何学运维ome answers below mentioned it's a reserved path for admin stuff.

But the letters, a and h together, is it an abbreviation or something?

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It comes from apphosting, the underscore is to make it more difficult to collide with some user provided URL.

Edit: I worked at Google, apphosting was the first name they selected for AppEngine, and this name still remains in some parts of the internal configuration.

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/_ah/ is a reserved URL path used by App Engine for features (mail, warmup, login, etc.) or administrative purposes.
Script handler and static file handler paths will never match this path.

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Maybe it's short for 'admin handler', but that's just a guess really.