It's specifically the definition of "match_case" in the AST that is affected: match_case = (pattern pattern, expr? guard, stmt* body) pattern = MatchAlways | MatchValue(expr value) | MatchConstant(constant value) | MatchSequence(pattern* patterns) | MatchMapping(expr* keys, pattern* patterns) | MatchClass(expr cls, pattern* patterns, identifier* extra_attrs, pattern* extra_patterns) | MatchRestOfSequence(identifier? target) -- A NULL entry in the MatchMapping key list handles capturing extra mapping keys | MatchAs(pattern? pattern, identifier target) | MatchOr(pattern* patterns) attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset) Relative to the PEP 642 AST, the notion of a "matchop" is gone - MatchValue always compares by equality, and there's a MatchConstant node for the identity comparisons against None, True, and False. The grammar, code generator, AST validator, and unparser are then updated to produce or consume the new AST nodes.