Look at the King Dedede moveset update.
http://www.smashbros.com/en_us/characters/kingdedede.html
He even says the word cancel. I found it very weird.
http://www.smashbros.com/en_us/characters/kingdedede.html
In other words, if you try to cancel with the same timing as an L-Cancel you'd suffer more lag instead of less.You can flip over and cancel it in midair.
However, if you try to cancel just before landing, you’ll make a fool of yourself, and you’ll be vulnerable for even longer, so watch out.
He even says the word cancel. I found it very weird.