Blender 2.66 Dynamic Topology only with constant detail size?

Indeed: 2.66 only had pixel size Dynamic Topology, yes, but that was 2013 and it was rather new then...There already was a checkbox for collapse edges though...Now it's 7 years later and Dyntopo is considered old-school by some;)

(I started using Blender in 2013...)

Thanks, Spikey, then it must be "Relative Detail" which is measured in pixels, whereas "Constant Detail", I think, is  related to Blender units.