Build contact nodes

I'm trying to build a new technology in Electric 7.00. For contact 
nodes, I specify metal layers and via layer as boxes for main example 
and other examples. Do the size of those boxes, or ratio of sizes 
between those boxes has effects on such nodes used in actual layout? If 
the size matters, do I have to keep the size/ratio for all examples in 
addition to the main example?

cheers,

Ming