I know the general, conservative, rule of thumb is to include wheels and handles in your measurements. AA actually shows including them in the diagram on their website.

Does anyone have a link to something official, on WNs site, which gives definitive guidance? One way or the other?

I'm humble enough to admit that just because I couldn't find it doesn't mean it's not there.

I'm looking for specific information, for a reason.

I'll agree, in advance, a bag which is just legal is likely to be overweight when packed "full". I'll agree, in advance, that it makes more sense to buy a bag which is legal on almost all airlines then only legal (due to wheel/handle measurements) on some airlines. No reason to have those discussions in this thread.