What is the name of the "\\?\" construct in windows?

Question

I had to help someone delete a folder that had weird characters in it that caused the path to be re-interepeted as a different path:

c:\test.     -> c:\test

It took me a while to recall the \\?\ construct, since I have no idea what it's called or how to search for it. Once I remembered it, though, it was easy:

\\?\c:\test. -> c:\test.

What is the name of this construct, that I (and others) may search for it?

Answer 1

I don't think it has an official name in widespread use, so I doubt that you'll get very far in any searches. It is described here: https://msdn.microsoft.com/en-gb/library/windows/desktop/aa365247.aspx#maxpath

The Windows API has many functions that also have Unicode versions to permit an extended-length path for a maximum total path length of 32,767 characters. This type of path is composed of components separated by backslashes, each up to the value returned in the lpMaximumComponentLength parameter of the GetVolumeInformation function (this value is commonly 255 characters). To specify an extended-length path, use the "\\?\" prefix. For example, "\\?\D:\very long path".

For this usage it might be called the extended-length path prefix. However the prefix serves other purposes, most specifically suppressing user mode path canonicalisation, the purpose that you were availing yourself of.

As you can see from comments to this answer, there are lots of varied opinions on the most suitable name. I think that we can all agree that there is no single officially used name for this thing!