
For example…
Scottish O League/Regional colour coded
W18 runs Blue, and is the same course as W20, W35, W40, M16, M55, M60, M35S, M40S.
W18S (there isn’t actually a W18L) runs Short Green and is the same course as W20S, W65, W70, W75, W80, W50S, W55S, W60S, W45S, M75, M80, M70S, M65S. W16 runs Green, so the choice for a W18 is either Blue or Short Green (it isn’t actually as its colour coded and you can run any course you like, but my point is about course/class combinations)
Scottish/UK Urban Leagues
There is no “official” W18 class, it is just Women’s Open (not to be confused with the other type of Women’s Open which is actually a shorter course (e.g. at the JK Sprint)). All W18s have to run with W20s, W21s & W35s or they have to do an “open” class. W16s run with W14s (on a shorter, easier course without crossing roads).
British Night Champs
W18L was 4.5km/160m and the same course as W45L, W50L, W21S, M65L, M18S, M45S & W50S
W18S was 3.5km/105m and the same course as W65L, W70L, W45S, W50S, M75L & M65S.
W16 (no S or L??) was 3.9km/125m and the same course as W55L, W60L, W20S, W35S, W40S, M70L, M55S, M60S. So the choice for a W18 was either a longer course or one shorter than W16
British Middle Distance Champs
W18 (no E, L or S) was 3.8km/105m and was the same course as W20, W50 & M70.
W16 was 3.2km/105m and was the same course as W60 & W65. No choice of course, and all 18s run the same.
British Long Distance Champs
W18L (there is an elite course) is 5.7km/280m and is the same course as M18S, M20S, W20L, W21S.
W18S is 4.1km/155m and is the same course as M80, M75S, M70S, W20S, W55S, W60S, W65S, W75.
W16A is 5.7km/255m and is the same course as M60S & W60L. W16A and W18L run the same distance!
So the choice for a “non-elite” W18 is the same length course as W16A or one shorter
The JK
The course/class combinations seem to be different again for the JK.
Day 1 (Sprint)
The only choice is W18E (which is a WRE) and is 3.3.km/30m, or Women Open 2.6km/15m. W16 is 2.8km/15m. So the only option for a “non-elite” W18 is a course shorter than W16
Day 2 (Middle)
W18L (there is an elite course) is 2.7km/85m and is the same course as M70S, M75L, W18L, W20L, W50S, W55S, W65L.
W18S is 2.5km/75m and is the same course as M75S, M80, W18S, W20S, W21V, W60S, W70L.
W16A is the same course as W18E (3.5km/80m) and is further than W18L
So the choice for a “non-elite” W18 is either elite or a course shorter than W16A
Day 3 (Classic)
W18L (there is an elite course) is 5.1km/185m and is the same course as M18S, M20S, M21V, W20L, W21S
W18S is 3.7km/115m and is the same course as M80, M70S, M75S, W75, W20S, W55S, W60S, W65S, W21V,
W16A is 4.9km/185m and is the same course as M55S and W60L.
So the choice for a “non-elite” W18 is either a longer course or one shorter than W16A
As you can see there appears to be a bit of a mix of the distances and the course/class combinations that are combined for “non-elite” W18s when compared with other age classes and especially when compared to W16s (if you look at W20s it is even more confusing!). I'm sure if you looked at all the other national/regional events you would find the same different mixture of course/class combinations.
I'm sure that there are rules and reasons for this, but it does strike me as slightly odd/confusing that it isn't more standardised and easy to understand, especially when often you have no idea of the course length/class combinations when you enter an event.