I came across this very full explanation of Wheel Alignment.

I found it interesting as it describes the different angles and why it is important that they are kept right.

http://www.nissantechnicianinfo.mobi/htmlv...nment.html FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 82k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Isn't that article mixing up caster angle and offset? (and hence trail)

eg it says a shopping cart has negative caster. It doesn't, it has zero caster angle and a caster offset. This offset gives it significant trail.
Similarly, a bike (which it uses for a positive caster angle example) does have positive caster angle but also has positive offset which then affects the trail.

I am not sure this is that important to the general gist of things but I think wikipedia explains this better...
https://en.wikipedia.org/wiki/Caster_angle FL2 2007 2.2d Auto SE. Baltic Blue.