Footnotes
The ubiquitous blue underlined “links” that we are all familiar with are the lobotomized sprog of a once-rich typology of links that were experimented with back when “hypertext” meant more than “the web” ( See history of link types ) But even Randy Trigg’s link taxonomy looks simplistic when compared to the subtleties and complexities of the footnote… “The Footnote: A Curious History” (Anthony Grafton)