"John Francis" <[EMAIL PROTECTED]> wrote: >> >> One black line and one white line is a "PAIR" >> of lines to me. Why would you need 4 lines >> to make up a pair? > >You don't. It's line *pairs* per mm if you count both the black >and the white line. If you only count the black lines (treating >the white as just the background) you get lines per mm.
That was my understanding. -- Mark Roberts Photography and writing www.robertstech.com
