Is your tile and tile installation up to acceptable standards and tolerances? Are you in a dispute with a builder or customer or vice versa about tile supply and installation quality?
You may find some guidance from Fair Trading NSW.
Extract from 'New South Wales GUIDE TO STANDARDS AND TOLERANCES':
Clause 12.9 Lippage (stepping) between tiles Lippage is inherent in all installation methods and may also be unavoidable due to the tile tolerances. Lippage may also be unavoidable where tiles larger than 150 mm x 150 mm are graded to a waste outlet, unless transverse cuts are incorporated. When measured with a straight edge, tiling is defective if the finished surface of the tiling is not flat and true to within a tolerance of ±4 mm in 2m from the required plane.
Tiling is defective if the lippage between two adjacent tiles exceeds 2 mm. In the case of tiles where the surface has been ground flat, for example polished tiles, tiling is defective if the lippage exceeds 1.5 mm; for joint widths of 3 mm or less the lippage should not exceed 1 mm.