The following article is rated "R." It will be best understood by mature audiences, and may not be suitable for readers under 17.

A friend phoned yesterday. "Ever since I can remember," he said, "I have been addressing two or more sides of packages that I send by parcel post. My return address and the address to which the package is going are written not only on the top of the package, but also on at least one other side.

"I do this because a package can become damaged in transit, a shipping label can become unglued, an address can become smudged. A postal clerk told me years ago that a package has a better chance to get through if there's an extra label on it. So I've been putting on extra labels. Right?"

"You have an honest face," I said. "If you say two shipping labels are better than one and three are better than two, I take your word for it."

"Good," my friend said. "Now, would it interest you to learn that I have just been turned away by a postal clerk who told me my package was 'unmailable' because it had two address labels on it instead of one? She even pointed out a sign I had never noticed before, and the sign made it clear that this is the official policy of the Postal Service. But I can't for the life of me figure out why they should have such a policy."

A spokesman for USPS said, "Golly, I've never heard about our suggesting two shipping labels. We certainly haven't done that in recent years, but it's possible that we used to do it a long time ago. Is your friend an older person?"

"No," I said, "he's just a boy my age. Why do you object to additional shipping labels?"

"We want one label," the spokesman said, "because we want it on the same side as the postage stamps. We don't want clerks seeing mailing addresses that are not accompanied by stamps, because that would mean the clerks would have to turn packages every which way to see if there were stamps on some other surface. That would slow down the automated systems we've set up."

The USPS does ask that a second mailing address and return address be placed inside the package -- for the very reasons you cited, old friend. If the outer label is damaged, the one inside the package will help get it delivered to the right place.

But I'm afraid you'll have to stop putting more than one label on the outside of the package, old pal. These young people don't realize how much stress they put on us mature guys when they ask us to unlearn things we've known all our lives. But now that it's been explained, I think you'll have to agree: Shipping labels that are not accompanied by immediately visible postage stamps would be confusing and cause delays. POSTSCRIPT

Do you remember the recent column in which a reader made fun of the Postal Service's antiquated scales that require clerks to jiggle weights until a balance is achieved, and then consult rate books to work out the math on postage requirements?

Wilbur F. Offtermatt of the USPS Research and Development labs has sent me some pictures of new, streamlined, electronic scales that USPS will soon be introducing. They appear to be just as sophisticated as the newest supermarket terminals.

Offtermatt tells me that because so many millions of dollars were involved, USPS evaluated the new scales with great caution before it decided to replace its "tremendously large stock" of mechanical scales. You can see the new scales on display in the lobby of USPS center in Merrifield, Va. IRANIAN JUSTICE

A dispatch from Iran says 11 supporters of a rival to Ayatollah Khomeini were arrested, and four hours later were executed by a firing squad.

Well, that certainly is one way to keep a court docket from becoming bogged down in delay.

But how would you like to be a hostage threatened with "trial" in a country like that? WASHINGTON WONDERLAND

The District of Columbia now has a "chief of protocol to assist Mayor Marion Barry in the conduct of international affairs." Guy Draper will get $36,000 a year for his services, but only if he can raise the money from private contributors and others.

I had hoped the job would go to Henry Kissinger, who could get the money from the Rockefellers. Or maybe from his friend the Pshaw.

When Barry ran for mayor, he promised that his administration would be innovative. He has certainly kept his word.

The idea of letting private donors pay the salaries of public officials is a real winner. How much do you suppose a housing inspector would cost?

Do you think the members of one "family" could afford a police chief?