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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.
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I think that you should read all the description (including the Notes) and not only that sentence to get what is expected to do.
NWSE takes no reductions, so you travel in the shape of a box, and you return to where you started.
NSWE has two consecutive opposites, so there are two reductions, and you do not travel at all.