Michael Hoffman wrote:

Source?

NRE Journey Planner:-
CHEAP DAY
Train Operator Most Train Operating Companies
Booking Deadlines No deadline - walk up fare
Discounts Discounts are available for all railcard holders
Refunds Full refund if wholly unused minus cancellation fee of GBP7.50
if processed online, or if processed at call centre.
Changes To Travel Plans GBP10.00 admin charge plus upgrade to next
appropriate walk up fare.
Conditions Reservations are not essential but are recommended on
certain services. Return journey must be made on same day as outward
travel.
Break Of Journey Valid for break of journey on outward and return
portion of ticket
Availability Available on most off-peak journeys on any days.
Validity Only valid for off peak travel on date shown on ticket. Not
valid for travel on some Monday to Friday peak services, especially
to/from London. Definition of peak period is dependent on route.

There do exist CDRs with a specific no Break of Journey restriction,
but I have personally never come across one, and they're rare enough
that staff would probably not know about them.

Neil