Where does it say that? Here's what I see in the '07 GCR:
[/b]
on page 341 of the 2007 GCR under section 9.1.4

9. Three (3) metal safety clips (75mm x 25mm x 3mm) shall be bolted,
or riveted, to the body at the top of the windshield. Two (2) clips
(same dimensions as above) shall be bolted or riveted to the cowl
and extend over the bottom edge of the windshield. Clips must
be spaced at least three hundred millimeters 300mm (11.8”) apart.....[/b]
apparently when i searched, i started in a different section of the GCR and hit in a different place. the production requirement is

Windshield/Rear Windows - Closed Cars: Closed cars may
retain their original windshields, and shall fit windshield
retention clips per GCR Section 9.[/b]
i think you and i found different things in "Section 9." sort of proves the point, maybe!