If you look - you'll find that the VTA reading on the collar at the arm lift lever is exactly 2.5mm (I think... I'm not at home to check the exact amount) higher than the actual VTA setting.
In other words - if you align 4.5 with the leading edge of the opening the silver arm lift lever comes through on the arm, the VTA will be set at 2mm.
I'll double check the numbers when I get home tonight - but I'm pretty sure it's a difference of 2.5mm.