The elusive nature of the world’s most famous brand, not to say the curious road to its definition, will be illuminated next week as never before when the Library of Congress unveils an addition to its permanent collection nicknamed “America’s baptismal document.” The document in question, a four-and-a-half-foot-by-eight-foot map, will be receiving national-treasure treatment more appropriate to a Jerry Bruckheimer blockbuster. After all, in its 200-year history, the library has never waited longer, nor paid more, to acquire any single object: 100 years and $10 million were spent obtaining this last surviving print of a map of the world made in 1507 by an obscure German cartographer, Martin Waldseemüller — a map that happens to feature the first use of a certain seven letter word with an understandable appeal to our de facto national library: “America.” To house this treasure, the National Institute of Standards and Technology (NIST) has built an encasement. At 2,000 pounds, its pressurized, argon-gas-filled environment is the largest case of its kind — big brother to the only other such cases NIST has made, those that protect the Declaration of Independence, the Constitution and the Bill of Rights.