Things that are used are likely to be referenced in the future. To the main point. When we talk about Internet scale naming. You'd better include time in the scale. We need URL's plus time-stamping.
Times come from a namespace - changes over the time.
Santa Claus is a well known name for an entity that does not exist. Abstract concept is a list. More from reference than the actually document. WWW is referencing less and less on the web. There are references to names that don't exist.