Any data I've seen refers to speed at 50'? Is this what's referred to here?
Yes, and as dangnamit said, it is a caclulated speed with a stall buffer. In most cases 1.3 Vs1.
For example, I have a flight manual for a single listing speeds based on weight for Vr (1.1 Vs1) follwed by speeds for 50' listed by weight as being 1.3Vs1. It is a TOSS because it provides the required safety margin over the stall as you accelerate towards Vx, Vy or cruise climb speed.
I look forward to hearing of any flight manual proposing increasing Vr beyond stated figures...
