Does dropbox calculate delta for files less than 4mb

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http://serverfault.com – As per How does dropbox version/upload large files? Dropbox uses 4mb blocksize. And if a 2mb portion of a block is modified complete 4mb block is uploaded on to dropbox. SO does it mean that for files <4mb dropbox need not calculate delta at all. It should simply upload the new file ? (HowTos)