How do you work out a restriction digestion map for a circular DNA plasmid? - (Nov/18/2006 )

I understand the linear dna digestion map but dont understand the one for circular DNA

An arbitrary position in the vector is chosen (usually the 1st base of the multi-cloning site) as base number 1. The base on the 3` side of base 1 is base number 2 and so on until you're all the way around the vector.

isn't this the same topic here http://www.protocol-online.org/forums/inde...showtopic=22242
or am i seeing double again???