You can specify the location for the internal cooling panels by referencing a 12-hour clock dial. Looking down at the tank from above, the "12:00" position would be the rear of the tank, directly opposite the side manway. The circumference of the tank is divided into twelve equal sections, each section equaling an "hour" on the clock. The "3:00" position would be on the right side of the tank--the "9:00" position would be on the left side. Some winemakers prefer the cooling panel ports to be positioned in the rear, but at a slight angle, so they specify the "10:00" position.
You can also specify the location of other fittings, such as a sample tap or thermometer fitting. Just reference the clock position and height of fitting from the floor.