Cliff & Bob,
Thank you for your responses. Apologies for the hidden code; some other forums have a "code" tag and I was trying to see if it would work as such in an effort to keep things neat... failed miserably.
I am heading out the door in about thirty minutes for a work trip and, if I'm lucky, I should be back Sunday so this response will be a bit brief.
Over the next couple of days I'll have some time to study the Python scopes and namespaces link. To be candid, I may well just rename the variables initially by appending P and S but - and I am afraid my knowledge of scripting as a whole is quite limited - moving the variables over to the Datatransfer class to make the whole thing more robust makes sense. I don't plan on having more than the two Arduinos at the moment but I do have a third Arduino (a Mega - don't think that'll make a difference though) available, and a single servo should Cliff wish to experiment a bit more. There are others in the local area who have been considering an Arduino solution and this may be able to help them out as they work on their layouts.
Last, regarding turnout names, my turnout table has ten rows. User names ST1-5 are assigned system names IT1-5 and PT1-5 are IT6-10. Is this not correct?