Designing using Easyeda and assembling the boards at jlcpcb is convenient. jlcpcb "economy assembly" requires distances between components to be 1 mm or more. So I add a design rules to check the distance between components is 1mm. 

I draw two components, a resistor and a SOT-23, 40 mil apart. Unfortunately, DRC says the components are only 20.7 mil apart.

DRC checks the distance between the silkscreen of the two components, and here it finds the dot that marks pin 1.
Perhaps the distance between the copper would be more appropriate. Or perhaps the distance between the 3D models of the components.