ID Start

ID Start is a character classification that marks which Unicode code points can begin a valid identifier in programming languages and text processing systems, such as variable names or function names. It includes letters from the Latin, Greek, Cyrillic, and many other scripts, along with certain ideographs, symbols like the underscore, and numeric characters from non-decimal systems. Crucially, it excludes digits, punctuation, and most symbols, ensuring that identifiers are easily distinguishable from numbers or operators. This classification is derived from a stable set of criteria, including general category assignments and specific script exceptions, and it provides a consistent foundation for parsers and compilers across different languages. By following this rule, developers can create identifiers that are both human-readable and machine-parseable, avoiding confusion with reserved keywords or literal values.