Incremental backups - differences What is the differene between:

BACKUP INCREMENTAL LEVEL 0 DATABASE; 


and

BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;


I read some manuals, but I don't get the idea.
An INCREMENTAL LEVEL 0 is a full backup of all used blocks in the database.
An INCREMENTAL LEVEL 1 CUMULATIVE is a backup of only the blocks that have changed since the last incremental backup.

... the definitions above paraphrased from the Glossary of Oracle Database Backup and Recovery User's Guide 11g Release 2.