One of the main reasons that I prefer paper documents is that it so easy to add a note or reference in the margin. You have just identified a new note for my copy of "Perl in a Nutshell". --thanks

You know :) notes are great ( ... What does _ mean? , About Special Underscore Filehandle ), but you could also perlbug and update for perlvar to mention _ ... cause its like a note :)

As I recall, Project Xanadu tried to address this in a way that did not require the original document to have either links or anchors - and without making a local copy of the original.