ID Compat Math Start - No
No is the designation for characters that do not qualify as valid starting symbols in mathematical identifier contexts under the “ID Compat Math Start” specification. This value applies to digits, punctuation, operators, and most symbols that cannot begin a mathematical variable or function name, even if they appear elsewhere in such identifiers. It also covers letters from scripts that are not considered compatible for math start positions, as well as combining marks and format characters. Essentially, any code point that fails the criteria for being a compatible math start, such as lacking the necessary compatibility decomposition or not being a letter of the appropriate category, is assigned the “No” value. This distinction helps parsers and algorithms correctly identify where mathematical expressions can begin unambiguously.