Does toe measurement require a flat patch?

I read through my car factory service manual on wheel alignment and they didn't said anything about a flat floor on toe measurement section, but they did mention to make sure the floor is absolutely flat when taking camber reading. This makes me wonder if a flat patch is not necessary for toe reading.

In general, all your setup work should be done on a flat surface. In saying that, as long as the surface isn't too poor, then the toe readings will usually be the least affected by the poor surface. This is not recommended though!