If you'd like to make yourself half-blind, take a bill larger than $1 out of your wallet or purse. Hold it up to a strong light.

See that faint gray strip that runs from upper edge to lower? That's your protection against counterfeiters. The Treasury Department began to implant this security strip in all American bills in 1990. Strips now appear on most bills in circulation.

But most is not all, and misunderstandings still erupt. Here's the story of a recent one, as relayed by a Levey informant. The incident took place at a gas station on Allentown Road in Fort Washington one night in late August.

As my informant went inside to pay for his gasoline, he walked into the middle of an ugly argument between the cashier and a woman who was trying to pay for her gas with a $10 bill.

The cashier had rejected the woman's ten spot, declaring it to be "no good." The bill was from a series of tens issued in 1981. It did not have the security strips that more modern bills possess. But it was still legal tender, the woman kept insisting.

The cashier wasn't having any. So a third customer exchanged $10 bills with the woman so she could pay for her gas and end the confrontation. My informant thought Levey ought to educate his trillions of readers about bills still in circulation that do not possess security strips but are legitimate nevertheless.

I'm happy to do it, with the help of operatives at the appropriate federal agencies. First up: Jim Marshall, a spokesman at the Bureau of Engraving and Printing.

Jim said that the U.S. government has not recalled any bills that lack security strips. In fact, Uncle Sam never recalls money for any reason. "The United States always honors its currency at full face value, no matter how old," Jim said. "It is not to be recalled."

Maria Ibanez, a public information specialist at the Treasury Department, said there's no such thing as an unspendable bill, as long as it was legal tender in the first place. "Currency before 1990 is all acceptable," she said.

Counterfeiting is still very much with us, of course, especially in an era of sophisticated photocopying machines. So what should a cashier do if he or she suspects that a bill is a fake?

John Tomlinson, assistant director of public affairs at the U.S. Secret Service, said that "whether before or after the Series 1990, the process is the same. Contact a local Secret Service office and read off some of the information on the bill. The field office will help determine if it's counterfeit. Or they can contact a bank. They provide the same service."

Let's hope this ends all ugliness between cashiers and customers. In case it doesn't, may I humbly suggest that all business owners find a pair of scissors and cut out today's deathless column?

If you don't think the prose is worth saving, please at least save the headline -- and tape it where your cashiers can see it. No reason to annoy perfectly good customers whose bills are old, but not bad.

Steve Bokat asked a searing question: "Have we become so impatient that we are not even concerned about running over a child?" Unfortunately, on the morning of Sept. 8, the answer was all too clear.

Steve and his wife were headed south on 16th Street NW, on their way to work. It was morning rush hour, so the pack was as thick as ever near the intersection of Arkansas Avenue. Steve's wife was driving. He was riding shotgun.

All of a sudden, a boy of about 9 tried to cross the street, in a marked crosswalk. The Bokats, who were in the left lane, stopped, as the law requires. But traffic in the right lane continued to whiz past.

"The boy crossed in front of our car and was peeking around it, waiting for a break in the traffic," Steve says. "Concerned that someone in the right lane might not be able to see him, I stuck my hand out the window, palm facing to the rear, in a signal to stop."

The next car to appear in the right lane was a large Mercedes, belonging to a large man "in a white shirt and tie." He stopped, and the boy crossed the street safely. But as the boy did so, Mr. Mercedes began to curse Steve out for delaying him. He finished his tirade by extending his middle finger in a universally recognized way.

A guy who gets that mad about being prevented from running over a child? I know a large man in a large Mercedes who needs a week off -- and who may want to ease back on coffee, too.

Dumb, dumb, dumb. Darn, darn, darn.

Maybe Dominique Neam will forgive me. She shouldn't. But maybe she believes in taking pity on oldsters.

In my column of Sept. 9, I listed many, many people whose birthdays happened to fall on the once-in-a-lifetime date of 9/9/99. I reported that Riva Neam was turning 9 that day. I thanked the source of that information, "Riva's mother, Dominique."

Nice going, Ro-bare.

You got it backward.

Dominique was the 9-year-old birthday girl on 9/9/99. Riva was and is the mom. Sorries to both.