Folgezettel are streams of thought. The branchings represent substreams which sometimes may become the mainstream themselves. The whole Folgezettel tree represents all the trails of thoughts and the possible continuation points.
Some people have random thoughts, some are more reactive. Building a Folgezettel tree is a way to gather your thoughts for an an extended period time, to focus on a few concepts that you want explore and perhaps think creatively, generating novel ideas. Building a Folgezettel tree
This aspect of Folgezettel is what I find most important.
There are several methods to implement Folgezettel :
Using Luhmann's numbering system.
Using links. However links are used for so many other things. Semantic relations, references, cross references, tags, etc. We need to differentiate which are the links for Folgezettel perhaps using different colors and labels
Using structure notes, notes that are in the second layer and contain indices to notes of the first layer
Using MOCs (Maps of Contents). This is equivalent to structure notes above.