What is the purpose of a text or graphic message? Isn't it to communicate? Wouldn't you suppose that the most important questions to ask when designing a message are

• What can I do to make sure the message is understood?
• What can I do to make sure the message is not misunderstood?

Here's one example of a foolish consistency

Signs along the road that warn you of a lower speed limit ahead used to say "REDUCE SPEED AHEAD" as in the first sign below. Supposedly the sign is telling you to reduce your speed.     Then somebody decided that you might already be going below the speed limit, so you might not have to reduce your speed. So they changed it to the second sign, supposedly meaning that the speed limit is about to be reduced. But now notice that the word "REDUCED" is longer than the word "REDUCE" so the lettering has to be reduced, making it harder to read.

The smart thing would have been to change the word to "LOWER" as in the third sign. That could mean that you have to lower your speed, or that the speed limit ahead will be lower. Either way, the intent is perfectly clear, and so is the lettering, because the lettering doesn't have to be reduced.

Here's another example

Signs with a graphic symbol telling you that the road might be slippery originated with an international standard in Europe as in the first sign below.    American highway designers liked the idea, but had a few objections. Tire tracks can't cross, they have to connect with the tires on the car, and the car doesn't tilt unless the road tilts. So they came up with the second sign.

But they lost the message. The international standard sign instantly conveys the idea of a car out of control. The American standard sign might just be a car with a drunken driver. Anyway, tire tracks really can cross, if the car spins.

Here's my final example

Coastal marine warnings of heavy weather used to be (in order of increasing severity) "small craft warning," "gale warning," "storm warning," and "hurricane warning" (the last used only in connection with a tropical cyclone). These terms are still used in other English-speaking countries.

But some American committee decided that if the last three obviously meant that a gale, storm, or hurricane is coming, then the first might be misunderstood to mean that a small craft is coming. Of course nobody would really believe that. A weather advisory is always a warning that some kind of weather is on its way. But in the U.S., "small craft warning" has been changed to "small craft advisory," supposedly meaning that it's an advisory to the operators of small craft, that is, small boats.

But a partial list of advisories and warnings issued by the National Weather Service includes not only "Heavy Snow Warning", "Winter Storm Warning," "High Wind Warning," "Freeze Warning," "Red Flag Warning" and "Gale Warning," but also "Snow Advisory," "Winter Weather Advisory." "High Surf Advisory," "Small Craft Advisory," "Lake Wind Advisory" and "Wind Advisory."

Now if a "small craft advisory" is a warning to small craft operators, is a "high surf advisory" a warning to high surf operators? Give me a break!