This British Standard specifies the construction, and dimensions
and tolerances, for rectangular and square surface plates for
use as working planes for engineering purposes, made of cast
iron or granite, in two size ranges, from 160 mm × 100 mm to
2 500 mm × 1 600 mm and from 12 in × 12 in to 96 in × 48 in, and in
four grades of accuracy.
The standard is applicable to new surface plates and to plates that are
being resurfaced after they have become worn.
In addition to the definitive requirements, this standard also requires
the items detailed in Clause 4 to be documented. For compliance with
this standard, both the definitive requirements and the documented
items have to be met.