A CHECKIN LIBVOLUME or a LABEL LIBVOLUME command is in progress, and the specified volume is needed. The server expects the volume to be inserted in the designated drive 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 drive, and then issue a REPLY command, along with the request ID, to tell the server that the volume has been inserted.