THERE WAS always a quaint and chivalrous ring to the rule, written into the military's "Code of Conduct," that an American serviceman who was taken prisoner could supply his captors with only four pieces of information: name, rank, serial number, date of birth - the minimum needed to ensure proper identification. The rule presupposed a war among gentlemen or, at least, among men who would be guided in their treatment of prisoners by a sense that they themselves might someday be behind barbed wire. Some commanders have always worried that the expectation of honorable captivity might rob soldiers of the incentive to give their all in battle, but the emphasis on what the Pentagon calls the "big four" items of information has remained in force since World War II.

But now change is coming. In the Korean War and again in Vietnam, serious flaws in the Code of Conduct became apparent. Under the physical and psychological pressures that Korean and Vietnamese captors so often brought to bear, not a few American prisoners broke down. The captors could play on the different interpretations of the code arising from the different instructions and traditions of the separate services. The guilt commonly felt by prisoners aware that under duress they had violated the code could be turned back against them by skillful prison interrogators. Moreover, openly or indirectly, American prisoners in Vietnam were the more vulnerable for the general awareness that North Vietnamese and Vietcong prisoners were not always being treated with the respect that the Americans felt was their due under the code. Far from it.

So it is that the pentagon, dutifully applying the lessons of the last war, has been reviewing the Code of Conduct. A committee including four former prisoners of war is recommending to the Secretary of Defense, who presumably will pass the committee's word to the Commander-in-Chief, that the actual experience of recent wars must be taken into account in the orders given American servicemen going into combat. Soldiers cannot be asked to perform as prisoners by standards that they are demonstrably unable to meet. The traditional concept of a prisoner's obligation to his comrades who are still in combat must be tempered by the realities - and, alas, they are realities - of torture, manipulation, weakness and pain.

The people rewriting the code are reported to be saddened and humbled by their knowledge that they are chaning rules for which American servicemen have suffered and even died in the past. No honorable person could avoid such misgivings. Yet those who send other Americans into combat have a responsibility to make rules that, within the context of the discipline of military service and the sure brutalization of war, are as sensitive as they can be to the dilemmas those men will face. This seems to us the purpose and spirit of the Pentagon's undertaking, and we think it is worthy of respect.