You can create and mount shadow sets using the $MOUNT system
service in a user-written program. Program calls to $MOUNT that
create, mount, or add devices to shadow sets use the same
syntax. To direct the system to perform any mount operation, you
construct a $MOUNT item list. The item list specifies the
virtual unit that represents the shadow set and the members
(physical devices) that the shadow set contains. The call to the
$MOUNT system service has the Example 5-1 illustrates MACRO-32
statements that produce a $MOUNT system service item list to
create and mount a shadow set. Example 5-1 Item List to Create
and Mount a Shadow Set The following list describes the elements
in Example 5-1: Notice that the virtual unit item descriptor
occurs first. This item descriptor specifies DSA23 as the name
of the virtual unit. See “Creating a Shadow Set ” for the proper
naming syntax for the virtual unit and shadow set The virtual
unit item descriptor is followed by two member-unit item
descriptors. Because Volume Shado