Understanding RMAN Backupset
RMAN uses backupsets by default.  The following commands will create a backup to a backupset:

RMAN&gt; backup database;
RMAN&gt; backup database plus archivelog;

This is assuming that you haven't changed the default RMAN parameters:
RMAN&gt; SHOW ALL;
...
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

&quot;Backup as backupset&quot; is not a valid command and will return a syntax error.
&quot;Backup as backupset database include current controlfile&quot; might be useful if you changed the default backup type to something other than a backupset (e.g. &quot;BACKUP TO COPY&quot;).
Source: Database Backup and Recovery Basics