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Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
Yeah, this wasn't clear to me. The test should have accounted for something like "1234" as unacceptable, if it was not okay.
It made me wonder if the author meant to say "characters" instead of "letters."