What does \\?\ mean when prepended to a file path

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A long read, but worth reading if you are in this domain: http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx

Extract:

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".

and:

The "\\?\" prefix can also be used with paths constructed according to
the universal naming convention (UNC). To specify such a path using
UNC, use the "\\?\UNC\" prefix. For example, "\\?\UNC\server\share",
where "server" is the name of the computer and "share" is the name of
the shared folder. These prefixes are not used as part of the path
itself. They indicate that the path should be passed to the system
with minimal modification, which means that you cannot use forward
slashes to represent path separators, or a period to represent the
current directory, or double dots to represent the parent directory.
Because you cannot use the "\\?\" prefix with a relative path,
relative paths are always limited to a total of MAX_PATH characters.

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