We're thinking of going from Paris Gare Lyon to Melun (Vaux le Vicomte).

I went to the transilien.com web site and looked up the departure & destinations.

I added plus/minus 1 hour to my selected time and a bunch of times show up.

I assume the "R" indicates a Regional train and the "D" indicates line D on the RER train.

So far no problem.

However, the time I like the best indicates a train number (91055) and shows a railway car but does not indicate either Regional or RER.

The only clue for me is that the duration of the trip is more like the Regional train (25 min) than the RER trains which take longer due to more stops.

Is there some way to determine if train 90155 is in fact Regional?

Thanks.

If you use www.bahn.com, it tells you:
10:49-11:14 Gare de Lyon-Melun RE91055

For this kind of inquiry, it helps to include the departure time: 10:49am, since pretty much all the train sites use the departure time to look up a particular train. Having a train number only requires some guess work.

I don't think it matters myself, you look at the board when you get there and find out the quay where it is leaving from. That train does have many stops, just not from Paris to Melun as that's very close to Paris. There are RER trains that seem like regular trains, actually, I've been on one to Auvers-sur-Oise, I connected to it in Pontoise, so whether it was called the RER or TER or whatever didn't matter to me.

this is the schedule, I believe
https://www.horairetrain.net/horaire...emigennes.html

The R stands for line R of the Transilien network and the D stands for line D of the RER network. As stated, just look at the departure times on the departing train board. You can also look at the Transilien website to see the end destination of the train, which will always be either Montargis, Laroche-Migennes or Montereau. Also, when you walk up to your departing track you will see a monitor at the beginning of the platform that lists all the stops that train will make if you want to double check that your are on the right train.

I think I see what is confusing you because on the Transilien website for this journey under the Itinerary Details instead of saying line R it says B01 and then underneath that it says train 91055. You'll notice this is only for trains with the destination of Laroche-Migennes and I'm assuming this is because Laroche-Migennes is beyond the Île-de-France and therefore not entirely part of the R line of the Transilien network. I would just forget about that detail because the fact remains that it is a train and all you'll need to do is match up the departing time on the overhead board and then double check the monitor at the beginning of the platform to insure that train stops at a Melun.

BTW, the first stop that both the B01 and line R make is in Melun so the train is non-stop from Gare de Lyon to Melun.

I should probably correct/amend what I said here because actually Montargis lies outside of the Île-de-France. I know from extensive experience on the Transilien trains that some of the Transilien network extends beyond the Île-de-France, such as the town of Gisors, a town from which I am frequently departing on my way to Paris.

Is the Melun station large enough to have ticket vending machines or should I buy a return ticket before leaving Gare de Lyon?

When I buy the ticket does it matter if it's an RER of Regional train as long as I'm at the correct track?

When I buy the ticket at a vending machine does it sell both RER and Regional tickets?

And maybe lastly, where does Mobilis ticket fit into this whole thing?

Melun is in Zone 5, so a Mobilis ticket covering Zones 1-5 will take you there and back on the RER. Not sure if those tickets are accepted on other types of trains.

After September 1, weekly Navigo passes will cover zones 1-5 for the same cost as the previous zones 1-2 pass. Here's the info, but in French only:

http://www.stif.org/IMG/pdf/STIF_-_C..._Tarifaire.pdf

Buy a Mobilis pass zones 1-5 and use it to not only to take the métro to Gare de Lyon but also for your round trip and then again in Paris until midnight. You can buy them from any ticket machine so do it before you take the métro to Gare de Lyon. It is valid on any form of public transport in zones 1 to 5.

http://vianavigo.com/en/tickets-and-fares/

Thanks.

So the Mobilis ticket is valid on the Metro, Regional and RER trains?

And a single zone 1-5 ticket (according to the web site) costs 16.60E and is valid for 1 day from midnight to midnight?

From my map it looks like the best way to get from Odeon to Gare de Lyon is to take the Metro #4 (direction Porte de Clignancourt)to Chatelet and #14 (direction Olympiades) to Gare de Lyon.

Is all of this Correct?

You can take those two metros if you like the Chatelet station.
If the surface traffic is moving, bus #63 is simpler. The bus stops at the outside the station building.
http://www.ratp.fr/informer/pdf/orie...loc=bus_paris/
Runs about every 10 minutes
http://www.ratp.fr/informer/pdf/orie...&loc=bus_paris

The bus route map:
http://www.ratp.fr/informer/pdf/orie...s_paris&fm=pdf

One more thing about the Mobilis pass...
You must write your last name (Nom), first name (Prénom) and the date you're using it on the pass before boarding a bus, train, etc.

http://www.ratp.fr/en/ratp/c_21148/mobilis/

The Mobilis Pass for zones 1-5 is valid on ANY TYPE of public transport in zones 1 to 5.

If going by métro line 4 to line 14 is correct. If by bus, then 63 and 87 are direct from just outside métro Odéon to Gare de Lyon but check the schedules so you aren't standing too long at the bus stop waiting.

Going back to the original message, Vaux-le-Vicomte makes a wonderful day trip from Paris. Here's my phototravelogue from just a few months ago (in Google Photos, be sure to click on the lower case i in the white circle to access the detailed captions):

https://goo.gl/photos/vfB3qve6MNuctD4t5