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:
    0  No Error
  -35  Volume with that name not found
  -36  I/O error
  -37  Bad volume name
  -47  One or more files are open on that volume
  -50  Parameter error (no volume name passed)
