A reader from Seoul says Stripes is misusing the word "troop." Properly, troop should refer to a unit of soldiers, not individual servicemembers. He referred to a headline that said: "Eight troops killed in Iraq."

Generally speaking, the reader is correct. Here's what the Associated Press Style Book says: "A troop, in its singular form, is a group of people, often military, or animals. Troops, in the plural, means several such groups." Stripes' own style book reinforces that concept.

There are exceptions. The AP book also says: "But when the plural appears with a large number, it is understood to mean individuals: 'There were an estimated 150,000 troops in Iraq.' (But not: 'Three troops were injured.')"

There is another exception, one that Stripes and other news organizations, including The AP, have felt compelled to adopt. It is to use "troops" when referring to a smaller group of servicemembers who comed from different services. The headline to which the reader refers, for instance, described what had happened to seven soldiers and one Marine. In often-tight headlines, it's not always possible to differentiate between various members of such a group.

But when all the servicemembers come from one service, the headline should say, soldiers or Marines, or airman or sailors.