The Maace Postulate

The Maace postulate, named after a friend of mine (Mason Hu) is that position should indicate function. That is, every design should include clear regions that have specific and unique functionality -- or put another way, an items position should tell you something about what it does.

A lot of web sites, for instance, litter the screen with links, navbars, ads and widgets; the content areas are often polluted and intermixed with ads and outlinks, and you have at least two or three sepeate navigational areas.

Maacer and I came upon this in an attempt to negotiate an interface for a Currency exchange site. He came up with the idea of using a T-style interface with the short term fields on one side and the long term fields on the other. There are three different types of trades; one requires only short term fields, one requires only long term fields, and the other required both; so the shape of the form gave you an immediate, graphic reflection of the trade type.

This clever tactic did more than just share a header: it allowed you to determine something vital about the oveall trade based on the shape of the layout, and you can understand something about each field based on its position. 

Even in an ordinary article this is true; the first and most substantial item (vertically) in an article is its title; the large bulk at the bottom is the content. Basic, yes; but many layouts either have no real regionality or violate their own rules by mixing links, ads and content in a fairly random hodgepodge of information.

The Maace postulate is not a rule for what goes where -- it simply states that everyhing has a natural place in a layout, and you should keep the general zones of a layout consistent and uniform. Especially in a serial layout (say, a book on birds), the layout should not vary, no matter how "artistic" that might be.

I Can See For Miles

One of the interesting factors in currency exchange is that the trading is done off multipe monitors, often at a farther than normal distance from the trader. For that reason the counterpoint to the Maace Postulate is, when attempting to provide visual distinctions between facets of a transaction, the more important the distinction, the farther away you should be able to stand and still notice the visual cues that mark the distinction.

For instance, you can see the currency in the above layout from yards away; you could probably detect the trade type from across the room. You would have to get in front of the monitor to see the exact amounts and be even closer to see the bidding partners.