I was in the final stages of ROTC summer camp or Infantry Officers Basic Training, probably the latter.  I was on an army bus with a lot of other guys, and we were going to some kind of training.  Everyone had on fatigues, but I felt that I had on my Class A uniform.  I figured we were going to go through the gas chamber, since that probably would have occurred late in our training, and someone was heard to remark, "They won't issue you one (a gas mask, I assumed) unless you are in fatigues"-which made me even more concerned about being out of uniform.  Then I noticed, however, that I did have on fatigues after all.  When the bus came to a stop, though, and everyone got off, I realized I didn't have my headgear-which I for some reason expected to be my service cap, not the fatigue cap.  I didn't know what to do, and I hesitated at the door of the bus.  Then the driver handed me a hat.  It was still not a fatigue cap, but a garrison cap.  I thought that would be all right, because it was interchangeable with the service cap, and I was much relieved.  As I left the bus, I noticed that the cap had a single bar on it--the light was too dim to tell whether it was silver or gold-but underneath the cloth, somewhere inside the cap, I could feel the captain's insignia, so I knew I could change the one on the outside.  I had to do it while walking, though, and it was difficult because of the dim light and the fact that the one on the outside was the pin-on type and therefore rather tedious to remove.  When I got inside the building where we had stopped, I was still fiddling with the cap insignia, and the rest of the guys had disappeared; try as I might, I couldn't locate them.