Further to [[User:Biogeographist|Biogeographist]]'s comments about what defines a zettelkasten, someone has also removed the Eminem example (https://en.wikipedia.org/w/index.php?title=Zettelkasten&type=revision&diff=1105779799&oldid=1105779647) which by the basest of definitions is a zettelkasten being slips of paper literally stored in a box. The continually well-documented path of the intellectual history of the tradition stemming out of the earlier Commonplace book tradition moved from notebooks to slips of paper indicates that many early examples are just this sort of collection. The optional addition of subject headings/topics/tags aided as a finding mechanism for some and was more common historically. Too much of the present definition on the page is dominated by the recently evolved definition of a zettelkasten as specifically practiced by Luhmann, who is the only well known example of a practitioner who heavily interlinked his cards as well as indexed them (though it should be noted that they were only scantly indexed as entry points into the threads of linked cards which followed). The broader historical perspective of the practice is being overly limited by the definition imprinted by a single example, the recent re-discovery of whom, has re-popularized a set of practices dating back to at least the sixteenth century.
It seems obvious that through the examples collected and the scholarship of Blair, Cevollini, Krajewski, and others that collections of notes on slips generally kept in some sort of container, usually a box or filing cabinet of some sort is the minimal definition of the practice. This practice is often supplemented by additional finding and linking methods. Relying on the presence of ''metadata'' is both a limiting (and too modern) perspective and not supported by the ever-growing numbers of historical examples within the space.
Beyond this there's also a modern over-reliance (especially in English speaking countries beginning around 2011 and after) on the use and popularity of the German word Zettelkasten which is not generally seen in the historically English and French speaking regions where "card index" and "fichier boîte" have been used for the same practices. This important fact was removed from the top level definition with revision https://en.wikipedia.org/w/index.php?title=Zettelkasten&type=revision&diff=1105779647&oldid=1105766061 and should also be reverted to better reflect the broader idea and history.
In short, the definition, construction, and evolution of this page/article overall has been terribly harmed by an early definition based only on Niklas Luhmann's practice as broadly defined within the horribly unsourced and underinformed blogosphere from approximately 2013 onward.
~~~~