System 80 memory circuit

[boxchester]

I am puzzled by something on the memory circuit diagram for the System 80 (drawing 4.2 CPU Board-2 Memory, in the technical manual). It seems to me that pins 3,6 and 10 of Z24 should go to A11,A12 and A13, but on the diagram they go to A10,A11 and A12. Does anyone know anything about this? I am quite prepared to admit it might be me that is crazy, but if anyone knows for sure it would be comforting to know.