A CHECKIN LIBVOLUME or a LABEL LIBVOLUME command is in progress, and the specified volume is needed. Mount the volume in the entry/exit port of the given library within the time limit specified in the message.
The server waits until a REPLY command is issued, or until the time limit expires.
Insert the volume into the library’s entry/exit port; and issue a REPLY command, along with the request ID, to tell the server that the volume has been inserted.