In 1944 the Bureau of Engraving and Printing experimented with a new paper for silver certificates. Some 1935A silver certificates were marked with a red 'R' to designate the regular paper; others were marked with a red 'S' indicating the 'Special' paper. A total of 1,184,000 of each type of note was printed. As is often the case with the government, no decision was reached regarding the superiority of one paper over another, so…nothing happened. In order to verify the 'R' or 'S' isn't 'added' to a note, compare any 'R' or 'S' note's serial number to these ranges.