How do you amortize copyright?

No, for two reasons: as a government work, it is not subject to copyright protection, but also as such a short phrase (one letter!) it could only be protected as a trademark. Which it isn't.

Nobody. It's public domain.

No. Trademarks can be renewed, copyrights cannot.

I reckon most people can by filling out loads of forms. But you can't just put a copyright sign on your work for it to valid. I think the above is not quite right: In the UK and in most of the world,...

A copyright pertains to ideas and purely intangible creations of the mind and is usually artistic in nature