What does a s slash s mean on a signature line?

What does a s slash s mean on a signature line?
/s/ on a signature line means that the signature is on the original document, not on the copy that you're holding. It is a representation that the original document is properly signed, but for some reason you only have an unsigned copy of the document. An unsigned copy of a document may be used for reference only or it may be a file copy (when it is not necessary to have a signed copy of the document).