What does _ah mean in Google App Engine?

Question

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 some answers below mentioned it's a reserved path for admin stuff.

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

Answer 1

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.