Sequential Multivolume
A sequential file that is contained on more than one volume. The file either may contain more data than can be held on a single volume, or it may have been deliberately divided over multiple volumes.
The following phrases apply only to device type TAPEFILE:
If none of these phrases is specified, the CLOSE statement causes the current volume to be positioned at its beginning.
For sequential multivolume files, a CLOSE statement that does not include a REEL or UNIT phrase has no effect on any volume other than the current volume.