I am a bit confused with RMAN books and documentation. Does a full RMAN backup copy more blocks than a Level 0 backup (by not skipping the empty blocks)? In the Oracle Documenation it says:

"A full backup reads the entire file and copies all blocks into the backup set, skipping only datafile blocks that have never been used."

In Metalink and Oracle Press books I have read the opposite, i.e., that only Level 0 skips the non-used blocks.

What is true?