The "S" in "Harry S. Truman" didn't really stand for anything. Therefore, the legend goes, you don't use a period after the "S." However, that's only a legend: Harry himself used a period -- you can see it in the signature, there -- plus, it's on the cover of his two-volume memoirs and on signage at his presidential library and museum. A fun story by the Washington Post and one I enjoyed illustrating with the lead art, here, and building the little tint-boxed sidebar. May 22, 2013.