With the trouser leg laid flat, we measure the cuff from seam to seam at the front only

We measure downwards from the point at which the heel meets the shoe
Plateau height: measured from top to bottom at the highest point

We lay out the item and measure along the centre from the outer edge of the buckle to the central hole (if there are 4 holes, measure to the second hole) 

We measure bags at the front in their customary position. The height is the vertical measurement, from the highest point to the bottom. The width is the horizontal measurement, from side to side at the widest point. The depth is the horizontal side measurement, from edge to edge. The length of the handle is measured from one end to the other following the perimeter

We measure this by wrapping a tape measure around the perimeter at the widest point