In the UK, for many places, there's a rather nifty thing you can add onto your train ticket - PlusBus. For normally a few quid more than the normal train ticket, you also get unlimited bus travel around that town for the day.
There are at least three official-looking sources of information on PlusBus. One of them is the National Rail Enquiries special offers section (pick a region then scroll down to P to find all the PLUSBUS entries), the PlusBus website, and often local authority sites as well.
My problem is that recently, I have discovered that the maps for a PlusBus region I use moderately often don't agree between all of these sites! This can cause problems when trying to use a PlusBus ticket in the area covered on one map but not the other, as neither myself nor the bus drivers are actually quite sure if the ticket is valid there or not...
As an example, we'll take the Hitchin zone:
- National Rail Enquiries page on the Hitchin PlusBus and PDF Map
- PlusBus page on the Hitchin zone and PDF Map
- Bushub online map of the Hitchin PlusBus zone
- Hertford Intalink May 2015 publication on PlusBus (Map on page 13)
Two of those maps show the south-west corner of the zone extending down to the Butterfield Business Park near Luton, two of those do not! I'm therefore unsure of if a PlusBus ticket is valid to there, or not, and so are the bus drivers... And I don't know which (if any of those) is the "correct" one to trust!
Where is the canonical validity of a UK PlusBus ticket defined? (And bonus marks - what does it say for the Hitchin zone and the Butterfield Business Park?)