AT&T MERLIN LEGEND Release 2.0 System Programming And Maintenance Manual page 48

System Programming and Maintenance (SPM)
Note that the feature module release number, not the version number of SPM,
determines whether the backup file is compressed or uncompressed.
Release 1.0 backups are uncompressed. Release 1.1 and 2.0 backups are
compressed. Uncompressed files take longer to restore. Before you begin a
backup procedure, note the following:
The communications system does not have to be idle during backup;
however, station programming is blocked.
Any objects that are in a maintenance-busy state are stored in that
state. When you restore system programming, these objects are
busied out, even if they have since been released from the
maintenance-busy state.
If you plan to store your backup file on a diskette, be prepared with a
DOS-formatted diskette. (DOS formatting can be done on a UNIX
system PC or a DOS PC.)
Uncompressed backup files are 100,000 - 210,000 kbytes in size;
compressed files are about 70,000 - 85,000 kbytes.
Maintenance data (error logs and other data used by qualified service
technicians) is not saved in the backup file.
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Backup