I wasn’t impressed by the clarity of the diagram, but it was almost certainly a section from a complete drawing of the 2-10-4 concerned.
I was amused by a reference to Trick ports on the New South Wales D58 class, where in an internal memo, the valves were described as the “Herr Trick” type to emphasise that it was a (German) person’s name. I just use a capital letter.
Peter