df, incorrect output, documentation not too clear

[David Lawyer]

I have no hard drive /dev/hdd.  But if I type "df /dev/hdd" it displays
the data for the current drive: hda2.  If you read the manual closely
enough, this is what it's supposed to do, but it's not too clear to a
person who just glances at it.

The output on my screen reads: Filesystem /dev/hdd and then it lists the
data for /dev/hda2 (but never displays the name hda2).  So the ouput
displayed on the screen should show /dev/hda2 as the file sytem.  The
manual and help should clearly point out that using say /dev/hdb2 as the
"FILE" will not find data for /dev/hdb2 (unless /dev/hdb2 is a (block
special) file located in the /dev/hdb2 filesystem).  This can be said
in fewer words for the --help option.  You might say that to use df, the
filesystem you want to check must be mounted.

                        David Lawyer