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World would not be the same if "Zero" was patented or if the numeric system was denied from usage. It is what you built from these factual elements that needs licensing not the elements themselves. By establishing a method to the public domain, the Inventive have to entrust themselves to be more ambitious and creative rather than to redeploy existing methods or deny others the methodology.
What about credits?
Zero license's primary agenda is collaborative progress. The 'Creative Commons' licenses may suffice additional requirements that are not available in Zero License - https://creativecommons.org
Font : Zeroes
Note: The font used for logo of 'ZERO' license is 'Zeroes' by Typodermic Fonts Inc.