The route of this lane is clearly incorrect and this can be confirmeed on other mapping and aerial photography, which clearly shows the route. As can be confirmed on FindMyStreet.co.uk USRN: 12105403
ROAD PAST BYWAYS, WHITFORD it is a road and can be legally used by all motor transport. However, it is not tarmac so make sure it has the right tags to stop 'normal' sat navs routing cars and delivery vans down it!

There is a through route here that can clearly be seen on aerial photography and can also be found on DCCs Dorset Explorer selecting Public Transport and Unclassified Roads. See https://gi.dorsetcouncil.gov.uk/dorsetexplorer#map=16.55/50.92560/-2.47104/0&layers=85/100/100//,1598/100/100//&basemap=1/100/100
It is fully legal for all traffic as an Unclassified Road, but is a 'green lane' and so should be annotated to keep it from being used by sat navs to route normal road users as you need a vehicle with off-road capability. It's also shown on FMS - See https://www.findmystreet.co.uk/map?gclid=CjwKCAjw0dKXBhBPEiwA2bmObXMelI05_367BYPNCGE4hGPzRaiZM0KBb72aujq-uzngVI9zNFo1ZhoCoOUQAvD_BwE
The continuation S of the A3030 to Down Lane should also have the same attributes.

USRN: 5701495
ROAD FROM TREBROWN BRIDGE TO TWINAWAYS, WIDEGATES
Classification: Neither M, A, B or C
Responsibility: Maintainable at public expense, Cornwall
Street State: Open
This road is completely missing from your map. It is fully legal for all vehicles but is a green lane and not suitable for anything except vehicles designed to go off-road. See FMS for detail.

~There is something wrong with the attributes of Coate Road, seemingly all the way along it, that does not allow sat navs to route motor traffic along it. It is a normal tarmac C road, as confirmed on Geoplace FindMyStreet - USRN: 18503422
WINDSOR DRIVE DEVIZES EAST TO COATE, COATE
Classification: C-road
Responsibility: Maintainable at public expense, Wiltshire
Street State: Open

The Byway from here S to the Leipzig Plantation is both suitable and legal for Motorcycles and 4WDs but presently the attributes are set incorrectly so Sat Navs will not plot it. It's not suitable for standard passenger cars (not tarmac). OS Maps and the Definitive Map show that this is a Byway Open to All Traffic (BOAT)

Byway Open to All Traffic CL14/54 is completely missing from the map here. It's legal for all traffic but you couldn't get a car down it so make sure it has the right permissions so sat navs don't start using it! Route is a straight line just NE of the green line on the map now, from the junction of Greenhouse and Howgrove to the bend in green lane just N of the green line. See https://app.bathnes.gov.uk/webforms/maps/?base=Ordnance%20Survey&center=51.365112936177006,-2.6902261376380925&zoom=18&categories=highwaysandtravel,highwaysandtravel_adoptedhighway,highwaysandtravel_publicrightsofway&wfslayers=mlyr-702749,mlyr-702750,mlyr-702751,mlyr-702754,mlyr-702753,mlyr-702732,mlyr-702752,mlyr-354381,mlyr-354638,mlyr-354409,mlyr-354630,mlyr-800194,mlyr-798597,mlyr-799028,mlyr-800017,mlyr-800219,mlyr-800222&wmslayers=mlyr-354398,mlyr-2523873

This footpath allowed my route planner to plot a cycling track along it - which would be illegal.

At this point the white road NW to the buildings is not part of Ruscombe Lane, but is LEIGH GATE LANE. The route of the brown dot dash line heading NE right up to Ridgeback Lane is all part of Ruscombe Lane, as is the white road S into W Milton. This is confirmed on FMS https://www.findmystreet.co.uk/map search for USRN 43201293 but also on all other maps. NB Devon Explorer calls it Runscombe but this is a typo, you can select historical maps to see the correct spelling from the 1800s https://gi.dorsetcouncil.gov.uk/dorsetexplorer#map=17.18/50.77160/-2.70306/0&layers=175/100/100//,85/100/100//,2/100/100//,15/100/100//&basemap=1/100/100

This is called "The White Bridge" and it is now fully open to motor traffic. You can search online to see this but we rode over it today. Please adjust so that open map based sat navs will use it.