Latices

Will someone explain these symbols for me?
I've been "lurking" on this list for about 9 months, and I don't
remember ever seeing an explanation for what looks vaguely like a
molecular model or archetecture.

4/3-------1/1
... ..
. . . . .
5/3-------5/4------15/8------45/32
/|\ /|\`. .,'/ \`.. .,'/
/ | \ / | \15/14/---\45/28/
/ 7/6-------7/4 \ | / \ | /
/,'. .`.\ /,'. `.\|/ \|/
4/3-.---.-1/1-.-----3/2-------9/8
. . . . .
.. ...
15/8------45/32