Windows programs and end users expect the system to remember
a current working directory for each volume and drive,
so that drive or volume prefixed relative paths like c:file.txt
can be used.
Absolute paths without a drive or volume
prefix are expected to use the "currently logged" volume or drive.
If the current working directory is somewhere in the c drive,
then the path /foo refers to c:/foo.
It must be possible to use the chdir function on a path
which specifies only a drive letter such as c:. This
will change to the previous working directory associated with that drive.
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