"all variable names shall be 1 to 3 letters of the set [a-z]" i think that works across almost all languages. if you really need more than 17,500 variable nam

"all variable names shall be 1 to 3 letters of the set [a-z]" i think that works across almost all languages. if you really need more than 17,500 variable names you are in some kind of hell already and stretching the spec to allow a 4th character will not increase your suffering.