Ok, yes maybe should have been more specific.
I am at this moment working with vaious different materials wich all have british standards for tolerances, i however have been given a design and layout that does not allow for tollerances, im arguing the case that there is no such thing as zero tolerance as we know, im in the sitution sadly that 5 mm on brickwork is making a visible difference, id like to get hold of the b.s regs for measurement or the relevants ISO, im covering myself.
can you help