How is the point system worked out when editing?

This is more out of being curious then anything else, I understand that a bot gives us points normal 1 or 2 when we edit a page. The other points that seem to be handed out when page has passed approve stage how is this worked out?

@hellscaretaker: each type of edit is given a weight for how important it is by the engineers, for things that are a single edit like adding a single character a specific point amount is given and for things like adding text a baseline point value is given and then a multiplier for word count, a quality multiplier is also given on a five star scale and the quality value defaults at 3 out of 5 stars. If a page you are working on is empty and you fill out large chunks of it that quality value increases and multiplies the reward.