A few days ago, I wrote about the loading areas outside supermarkets and the attendants who are hired to work there.

Grocery chains hire attendants for two purposes: to help load purchases into the cars of customers, and to guard those purchases from theft while the customer is bringing his or her car around.

The major chains have given high priority to stamping out thievery at the loading docks, but they have not been completely successful. Shopping bags filled with groceries continue to disappear occasionally.

The column listed several things a prudent shopper can do. One suggestion was that the register tape should not be left on the dock with the groceries. It should be taken along by the customer who has gone off to fetch his car. If the groceries are stolen, the customer has proof of what was taken.

Within two days after that column was published, three friends informed me they had seen copies of it posted on employee bulletin boards in three Giant supermarkets. And yesterday I received a letter from M. K., who wrote that on the very day the column appeared she saw a mother and her small child pull up to the loading dock of the Safeway store at 5545 Connecticut Ave. NW to find that all their groceries were gone.

"I understood your text completely," M. K. wrote, "and I wrote to Consumer Relations at Giant and Safeway. I felt your comments should be evaluated and perhaps included in the training of checkout cashiers. I have now received my first response, which you will find enclosed. I hope that it will brighten your day as it did mine."

What was enclosed was a letter from Barbara B. Beizer, consumer affairs manager for Safeway. The letter thanked M.K. for forwarding a copy of my column and said:

"We are sending copies of the column to all our stores and district managers to alert them to this important detail which could make a crucial difference in the event of such an incident of thievery. We are advising our management people to instruct their employees to follow the policy of placing the receipt in a customer's hand with some explanation of the rationale behind this new practice."

So the next time a supermarket cashier hands you a register tape instead of sticking it into a bag, say "Thank you." Your neighborhood grocer catches a lot of hell for high food prices (which he can't control any more than you or I can), so it's a pleasure to give him credit for the good things he does.