/etc/fstab-options-(user option?)

[imand]

Hi
As you know user option allow an ordinary user to mount the file sytstem . The name of the mounting user is written to matb so that he can unmount the filesystem again.
I used this option in /etc/fstab for my /dev/hda7
mounted /dev/hda7 in /mnt/hda7 with iman's user.
so only this user can unmount the device (and root can too).
tried to test what happen if I try to unmount this device with other users, but when I did that, this messege appeared:
umount:only root can unmount /dev/hda7 from /mnt/hda7
but iman's user can do that too.
this messege appeare when you don't set user option in /etc/fstab or set user option but mount your device with root,too.
what did I miss?
what's wrong here?

thanks for your attention