I'm a little confused with RMAN terminology. Can someone help me out here.

1) In what scenario would a DBA initiate a "Full" backup versus doing an "full incremental level 0" backup? I don't see why a DBA would ever kick off the former. Might as well do a "level 0" instead everytime, right?

2) Below are the definitions of "Full" and "Incremental" backups from the TRM. Now what is a "Whole" database backup (referred to in the below 'Note')?! Per my understanding - full, whole, and incremental only backup used data blocks in the datafiles.
Thanks, Anand

Here are the definitions from the TRM.

Backup Type : Definition
1) Full :
A backup that is not incremental. A full backup includes all used data blocks in the datafiles. Full backups of control files and archived logs always include all blocks in the files.

Note: A full backup is different from a whole database backup, which is a backup of all datafiles and the current control file.

2) Incremental
A backup of datafiles that includes only the blocks that have changed since a previous incremental backup. Incremental backups require a full or incremental level 0 backup to serve as a basis.