NOTE: If it says "length" you only measure the length, and if it says "circumference" you measure around the body. The abbrevations is in Norwegian.
HL (neck length): Measure from the centre of the shoulder blades down to the sternum.
BL (chest length): Measure from the sternum, down between the front legs and back to where the harness should stop under the dog.
BO (chest circumference): Measure around the chest/body where the harness should stop.
RL (back length): Measured from the center of the shoulder blades to where the harness should stop along the back.
Under you will find a picture which shows the measurements.
Under 49 cm in chest circumference
50-69 cm in chest circumference
Over 70 cm in chest circumference