The famous Zettelkasten from Niklas Luhmann was an analog device. Luhmann has written down ideas on physical sheet of papers and put them into a tray. This approach has cons and advantages. For sure, the approach is more time consuming than writing the notes into a computer. The following blog article describes a much faster way in making notes.
Instead of describing a concrete Zettelkasten simulator like Obsidian or the ZKN3 software the idea is to use an common of the shelf outliner software. Such programs are available for all operating systems and it is even possible to write such application from scratch. Outliner programs have evolved over the time. A modern software contains of a left pane and a right pane, and the user can enter text and images. The text can formatted wth rich style which includes colors, tables and different fonts.
The screenshot shows the interaction with cherrytree outliner which is available in he debian repository. The surprising situation is, that all the nodes are grouped on the same hierarchical level. Also they are numbered manual. This is perhaps the most obvious difference to a normal note taking file.
If the user likes to add a new note in between two existing one, the only way in doing so is to branch down. Branch down means to increase the depth of the numbering system. The principle is descriped in detail in the literature around the Luhmann zettelkasten and shouldn't repeated here.
For reason of convenience it is possible to add an index which has the number 0. The index works similar to the register in a book which is located at the end. Important keywords are listed and the jumping address is shown. Most outliner software have no ability to insert links directly, so the user writes down the link in square brackets. And then he has to scroll down in the left pane to find a certain node.
In a physical Zettelkasten a node is equal to a card. The idea is that the maximum size of a node is around 500 byte. More characters won't fit on an index card. If the user likes to write down more information he has to create a new node.
After a while, hundred of theses are crated by the user in the outliner software. The information can be requested with many ways. The easiest form is to scroll in the nodes, another option is to use the full text search or to take advantage of the manual created index.
There is no need to create a bibliography section. Instead, external www links and book references as well can be copied and pasted into the nodes directly. But nobody prevents that the user can create a separate bibliography similar to a bibtex file if he likes.