Design Pet Peeve #7:  Lack of Correlation. Correlation means agreement among parts, interrelationship, or connection.  In design, the short meaning is that once an element of any kind is introduced into a system or project, the look, size, and placement of that element should remain the same throughout its use.  It can be color-coding, type styles, shapes, sizes, placement, or the like.  But, a breakdown of standardized usage in a design can produce a confusing or downright dangerous situation.  I’ll give one example of poor correlation: E-mail and document-forwarding sites allow you to include attachments with the prompt button marked “attach” or “attachment.”  But on some sites, when you get to the point where you have an attachment ready to include, the prompt button says “enclose,” or worse, “open,” instead of “attach.”  This may seem like a minor point, but if you were to expand the dilemma created by this type of poor correlation to something larger, like a web site or the logic of a building’s layout, the results would be confusion and frustration.  If extrapolated to the scale of an airport communications system, the results could border on catastrophic