On Rosh Hashana night, it is customary to greet one another with "לשנה טובה תכתב (ותחתם)" (Rama 582:9, MB). People (in my experience) and machzorim (Rosh Hashana prayer books) treat this as formulaic, with no variation from the specified text. (Specific customs vary, with, e.g., some adding "לאלתר לחיים טובים ולשלום", but whatever custom people may have, they stick to it, rather than saying wholly different things like the suggestions below.) It's so formulaic that some people (purposely) don't even decline the verbs for number and gender.
- Is it correct to treat the greeting as an immutable formula, the way people and machzorim do? (E.g., is that how we should read the Rama?) Sources, please.
And if it's correct (or correct according to some sources), then:
- Why is there such a formulaic greeting? Why not use whatever other wording we may think of, like "לשנה טובה ומתוקה תכתב ותחתם" or "תכתב בספר החיים" or "תכתב ותחתם לשנה טובה"?