Holes in fittings are often slotted to increase tolerance. When used with sections that are cold-formed by bending, such as angles or channels, sufficient space must be allowed for washers to sit ‘flat’ before they meet the radius of the bend. The suggested values in the tables below are based on an internal bending radius of ‘2t’ for the plate.

They also give the recommended edge distance to edges.  The edge dimensions are nominally rounded up.  The minimum dimensions are for detailing purposes only.  Design requirements may increase the figures.