Given a mount point, H5F_UNMOUNT dissociates the mount point's file from the file mounted there. This function does not close either file.
The mount point can be either the group in the parent or the root group of the mounted file (both groups have the same name). If the mount point was opened before the mount then it is the group in the parent; if it was opened after the mount then it is the root group of the child.
loc_id is either a file or group identifier and
name is relative to