Had the priveledge this morning of looking at a marked SVRy caboose marker light that belongs to a private collector. One interesting feature is that it is marked SVRR rather than SVRy. He collects locks and other railroadiana and say that he has seen Sumpter Valley stuff with SVRR, SVRy, and SVRy Co. Is there any rhyme or reason why they used these different designations? Do they each relate to a particular time frame?