In message , at 15:57:55 on
Sat, 2 Nov 2013, Roger remarked:
They are just a class of season ticket.

Going into extreme pedantry mode they are not a season ticket at all.

Yes they are. It's an "all London" [or whatever] free-of-charge season
ticket. It's certainly not PAYG.

They are a form of pass or permit which are different products so far
as the Oyster system is concerned.

In what way are they treated differently by the gates?

The gates treat them as Freedom passes.

And in what way does that differ from being treated as a season?

Freedom Passes cannot be used on National Rail before a certain
time (09:30?) on weekdays.

So it's a class (remember be using that word?) of season ticket which is
only valid after a certain time on some routes.

That's not a significant difference (compared for example with the
difference between a regular season and a one-off point to point ticket,
or a PAYG purse).

--
Roland Perry