I'm sorry, but, once again, this is simply wrong.  I would get out my hundred-year-old Black's Law Dictionary and quote from the definition of "currency" and the half-dozen cases that explain in detail why currency, not only the concept but the actual etymology of the word itself, is subjectively determined by market acceptance, but I've posted it here before and I'm not sure that would convince you, regardless.  Just search my posts in the legal section if you're interested.  Or we could go through the hundreds of years of human history during which currency was not constant, and catalogue the millions of people who lived and died their entire lives using currency that was not an objective unit of value.  Or we can point to any of the dozens of fiat currencies in existence today whose values change continuously, yet which billions of people use as currencies regardless.  But we've already done that, I think, and it didn't convince you either.  So, frankly I can't say there's much left to point out.  Your ridiculous view of currency as a defined "unit" requires someone to back that definition against the collective force of billions of market participants, which is objectively impossible.  Stick with Federal Reserve Notes if you think otherwise.  That sounds like the closest thing to what you seem to want anyways.  Good luck.