https://en.wikipedia.org/wiki/Edge_index

An indication of the state-of-the-art in punch card systems from 1951 to 1958, particularly with respect to practical applications.

Casey, Robert S., James W. Perry, Madeline M. Berry, and Allen Kent. Punched Cards: Their Applications To Science And Industry. 2nd ed. 1951. Reprint, New York: Reinhold Publishing Corporation, 1958. http://archive.org/details/PunchedCardsTheirApplicationsToScienceAndIndustry.

Begun, George M. “Making Your Own Punched Cards.” Journal of Chemical Education 32, no. 6 (June 1, 1955): 328. https://doi.org/10.1021/ed032p328.

George Begun used a template of "heavy galvanized iron" to drill holes into his 5 x 8" index cards to create his own edge-noted card system for use in his chemistry work. Rather than using commercially made sorting needles, he recommended the use of a ice pick with a dulled point "for safety".

Edge-Notched Cards: A queryable database...made of paper by [[Soren Bjornstad]]

https://warrenpaper.com/product/1001/

This is similar to the idea of edge notched cards, but is done visually instead of cutting the cards. It's also seen in the Pile of Index Card method which uses a variety of marks on gridded cards.

reply to u/stjeromeslibido at https://www.reddit.com/r/antinet/comments/10lqfsn/comment/j63y2k9/?utm_source=reddit&utm_medium=web2x&context=3

Every card has holes pre-punched into it in exactly the same place (see the photo in the original post at the top) so that one might put a knitting needle (or other thin instrument) through the whole deck in each of the positions. Then one should decide on what each hole's meaning will be by position.

As an example, imagine you're using your cards in a rolodex fashion and you want to distinguish the six categories: family, friends, service providers, neighbors, co-workers, and organizations/businesses. For family members you cut/remove the additional paper between the first hole (representing "family") and the edge of the paper. You do the same thing for all the other cards based on their respective categories. So, for example, your brother Joe who lives across the street from you and works with you at the office in the family business would have cuts removed for positions 1, 4, and 5. For an entity that fits all six categories, cuts would be made such that the sheet would no longer stay in u/I-love-teal (the original poster's) six ring binder notebook.

At the end of the year you want to send Christmas cards to your friends, family and neighbors, so you put the knitting needles into position 1 and pull up separating your family out, then you repeat for positions 4 and 5 until you have your full list. (Pro tip: you probably wouldn't want to pull them out of the deck completely, but might rather pull them up and set them at a 90 degree angle thus preventing you from needing to do the work of refiling them all in a particular order.)

Obviously if you have multi-row edge punches or dozens of edge notches you can discern a lot more categories or data types using basic logic. Just abstract this to your particular note card system. Herman Hollerith used this in early versions of the U.S. Census in the late 1800s and it and variations were used heavily in early computer programming applications.

A variation of this sort of trick can also be done by coloring in (or not) the edges of parts of your cards as well. See for example the general suggestions in these photos which help to layout the idea of the "Pile of Index Card" system used back in 2006 with respect to Getting Things Done (GTD) philosophy:

• https://www.flickr.com/photos/hawkexpress/189967397/
• https://www.flickr.com/photos/aki_oda/2684257358
• https://www.flickr.com/photos/hawkexpress/189972896

On my mathematics specific notes which I generally put on graph paper cards, I use colored edge "notches" like these to represent broad categories like theorems, proofs, definitions, corollaries, etc. or method of proof (induction, direct, contradiction, contraposition, construction, exhaustion, probabilistic, combinatorial, etc.) This makes finding specific cards a bit easier as I tip through various sections.

A historian might use colored edges to visually label dates by decades or centuries depending on the timespan of their studies. The uses can be endless and can be specific to your field of study or needs.

Some might also attach the idea of tags/categories to the colors of their cards, so you might use white cards for ideas which are your own, yellow cards which are quotes of others' material, blue cards which represent synopses of other's ideas, etc. One might also profitably use a multi-pen with different colored inks to represent these sorts of meta-data as well.

The variations are endless...

reply to IvanFerrero at https://forum.zettelkasten.de/discussion/1740/anybody-using-this-approach-to-manage-contacts-how#latest

Many of the digital note taking tools that run off of text allow you to add metadata to your basic text files (as YAML headers, inline with a key:: value pair, or via #tags). Many of them have search functionality or use other programmatic means like query blocks, DataView, DataViewJS, etc. for doing queries on your files to get back lists, tables, charts, etc. of the data you're looking for.

The DataView repository has some good examples of how this works with something like Obsidian. Fortunately if you're using simple text files you can usually put them into one or more platforms to get the data and affordances you want out of them individually.

As an example, I have a script block in my daily note in Obsidian for birthdays in my notes that fall on today's date:

```dataview LIST birthday FROM "Lists/People" WHERE birthday.day = date(2023-01-18).day ```

If I put the text birthday:: 1927-12-08 into a note about Niklas Luhmann, his name and birthday would appear in my daily note on his birthday. One can use similar functionality to create tables of books they read with titles, authors, ratings, dates read, etc. or a variety of other data input which parses through your plaintext files. Services like Obsidian, Logseq, et al. are getting better about allowing these types of programmatic searches for users without backgrounds in programming and various communities usually provide help for pre-made little snippets like the one above that one can cut and paste into their notes to get the outputs that they need. Another Obsidian based example that uses text files for tracking academic journal articles can be found at https://nataliekraneiss.com/your-academic-reading-list-in-obsidian/; I'm sure there are similar versions for other text-based platforms.

In pre-digital times, for a manual version of a rolodex like this in paper, one could use different color cards as pseudo-tags (doctors are on yellow cards, family members on blue cards, friends on green cards, etc.) or adding edge notches or even tabs to represent different types of metadata. See for example the edge colored cards in Hawkexpress' Pile of Index Cards: https://www.flickr.com/photos/hawkexpress/albums/72157594200490122

I remember also seeing this as an indexing system for index cards in 2007. https://www.flickr.com/photos/hawkexpress/sets/72157594200490122/

It's not too dissimilar a pattern from the early 20th century edge-notched cards which were used to make sorting collections easier. https://en.wikipedia.org/wiki/Edge-notched_card Of course doing this for a notebook isn't going to work as easily.

Reply to https://www.reddit.com/r/commonplacebook/comments/oq12xs/has_anyone_used_this_indexing_system_curious_what/

https://hackaday.com/2019/06/18/before-computers-notched-card-databases/

Originally suggested by Alan Levine. Some interesting specific examples here, but I've been aware of the concept for a while.