This relation is used when a window is said to be large. (display-position-data '(junction-k2-w2 electrical-junction)) with a value = '((42 100)) means put the icon
for k2-w2, which is an electrical junction at position (42, 100) on the screen. Any extra data
in the position spec, e.g. (250 203 :T-1-Position :Top ...) is passed through to the item
when it is created as its init-plist. In this case it means attach the terminal t-1-position
to the top of the icon.