Abbe's principle of alignment is used in measurements made in .................

The fit on a hole-shaft pair system is specified as $$H7$$-$$s6$$. The type of fit is

The diameter of the best wire to measure the effective diameter of a metric screw threads of $$0.5$$ $$mm$$ pitch is ......... $$mm$$

In mass manufacturing, two holes in a plate type of component are ideally located with the help of