We've never had them reject a design and frankly, many approved designs are quite similar to each other. We HAVE had them reject a name and ask for it to be changed slightly, but it was never a big issue. Please keep in mind that you do NOT have to register a tartan you design. It does make it 'official' and record it for posterity, but isn't a requirement for the tartan to 'exist'. Example: We (several of our staff) love the Philadelphia Flyers and designed an orange and black tartan to wear with our jerseys. We didn't register it, but we wear it proudly!
If the tartan is close to another tartan (1-4 thread difference, or something like that), they will not consider the new tartan different enough to register it as a unique tartan.
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