I was reading through the addendum yesterday and have a question about the diagram on Page 10. The 6-81499 Lionel LCS DB-9 Cable with Power supply has connections to the Ser2 and Legacy Command Base. My question, what is the component labelled "AC" and what is the wire running into from the command base? It may be an obvious answer, but I've researched it and can't quite figure it out.
Thanks