1. A method of conveying currentness information about a document that is one of a plurality of documents, comprising: at every date j of a sequence of dates, and for every document i of the plurality of documents, having a currentness authority, that includes at least one processor, compute individual currentness status information Ci about i by digitally signing information identifying i, date j and an indication whether i continues to be valid, or is obsolete, or is suspended, wherein the currentness authority computes the individual currentness status information Ci independently of a request for the document i; providing the digitally signed currentness status information Ci to a responder that includes at least one processor; for each document i in a plurality of documents, having the responder store the latest received Ci; and in response to an inquiry about currentness status of document i, having the responder provide the latest received Ci.