MP nmount (volname)  ->  err

Unmounts any currently mounted volume.

err             integer       returns the error which occured. A value of 
                                        zero indicates no error occured. See below 
                                        for a list of possible errors.

volname      string (max. 27)      contains the volume name you want 
                                        to unmount. Actually this may be a full path 
                                        to a file or folder (max. length 255). As long 
                                        as it starts with a volume name it will be 
                                        succesfully unmounted. If the file or folder 
                                        does not exist no error will be returned.

For AppleShare volumes this is sufficient to disconnect from the server. Other non-ejectable volumes are unmounted as if the user moved its icon to the trash. Ejectable volumes are placed offline, but not ejected!!!
The volume with the System Folder or with the Virtual Memory storage file can not be unmounted and, when trying to do so, will return an error.

Use this function to disconnect from a server if you are sure the volume you are handling is a server volume.

Note: The length specified with a string is the maximum length possible. The external does not test for the size of the variables. Please, declare the string you use to the correct length. Use of these commands inside the Debugger window is not recommended.

Possible errors:
      o Error
  35  olume with that name not found
  36  /O error
  37  ad volume name
  47  ne or more files are open on that volume
  50  arameter error (no volume name passed)
  55  olume off-line or ejected

And other errors Apple hasn't told me about.