It's not an actual attested English word, but the term "metascript" comes reasonably close to a concept I would like to express in a proposal I am preparing. A "metascript" as I am defining it, is a script such as Latin, Cyrillic or Arabic, that has been extended from a common core in a wide variety of ways to serve the needs of a wide variety of languages. A resulting aspect of metascripts is that they contain far more characters than are needed for any single use of the script. I find the concept useful in explaining why I have made certain decisions in my proposal, but would prefer to use a standard term for the concept if there is one.
