9. Sitting eye height

　

	Definition:	Vertical distance from the sitting surface to the inner canthus (corner) of the eye.
	Applications:	Centre of the visual field; reference datum for location of visual display, ‘reach’ dimension for sight lines, defining maximal acceptable height of visual obstructions; optical sighting devices for prolonged use should be adjustable for the range of users.
	Corrections:	10mm for heavy outdoor clothing; up to 40mm reduction for ‘sitting slump’; seat compression.

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