Think of Maori tattoos like a collection of facts about the person bearing the tattoo. Scarification is the same idea, except those facts are REALLY important, too important for a tattoo which is less memorable than a scar. Examples of facts would be: family of origin, affilliated organization, past achievements, place of birth, occupation, etc. Markings would be born on the front of the body to make introductions very quick and easy: you can just look at a stranger and you already know a lot about him or her, and assuming you have good manners, you would also know what etiquette to observe when meeting for the first time.