It's tosh
Copied from IVA manual;
MAX DISTANCE FROM SIDE (mm)
400 (Min separation 500 unless vehicle width is less than 1400, where Min separation 400) see note 6 below
MAX HEIGHT (mm)
1500 or if impracticable 2300 for side direction indicators and 2100 for front and rear direction indicators
MIN HEIGHT (mm)
350
ANGLES OF VISIBILITY
a. Horizontal
i. 800 outwards 450 inwards.
ii. (SIDE REPEATER) To the rear between 50 and 600 outboard.
b. Vertical
i. < 750mm above the ground 150 above and 50 below horizontal.
ii. Otherwise 150 above and below horizontal.
Thats the IVA manual Revision: 1 Date: 27/03/2009/* although i accept it may have be re-issued , it's the latest version I could find
from MEV -
http://www.mevltd.co.uk/downloads.html
Sean