That only means that the railroad diagram is not a direct translation of the original grammar. Conversely, there are more than enough BNF variants that can do t

That only means that the railroad diagram is not a direct translation of the original grammar. Conversely, there are more than enough BNF variants that can do the equivalent inlining. I will personally denote your example as: if_stmt: 'if' named_expression ':' block ('elif' named_expression ':' block)* ('else' ':' block)? ...which is no more complex than the original diagram, and reads much easily at least for me. In fact, that "original grammar" does support the equivalent syntax because it's a direct input to Python's PEG code generator. I don't know why `if_stmt` was described in that way, but such duplication is often done for readability and hardly surprising.