On Wed, 13 Feb 2008 00:04:19 GMT, wrote:

I can't remember what kind is at Gunnersbury etc, but on the Bakerloo
shared sections, I think the markers are NR style.

For both the Underground and Overground, right?

The Overground has "3 car stop" and "6 car stop" signs (or "S car
stop" at some stations instead),

I thought the "S car stop" was what they used for both on the District,
though I could be wrong.

though 6 car trains never run (and it
may not even be possible).

Why would it not be possible?

The power supply may not be able to cope with the current drawn by a
6-car 313 accelerating.