XID Continue

XID Continue is a character classification that determines which code points can appear after the first character in a programming identifier, as defined by the Unicode Standard's Identifier and Pattern Syntax. It includes letters, digits, underscore, combining marks, and certain other characters, specifically excluding spaces, punctuation, and symbols that could break identifier parsing. This set is a superset of the older "ID Continue" but adds characters like middle dot and certain modifier letters that are safe for identifiers in modern languages. Its primary use is in lexical analyzers and compilers to validate whether a given character can legally continue an identifier once it has started, ensuring that names like `variable2` or `_temp` are valid while `my-name` or `a b` are not. Languages such as Java, Python, and Rust align their identifier rules with XID Continue, though they may add language specific restrictions, like disallowing certain invisible or format characters.