The [`role` key](00001006020000#role) defines what kind of zettel you are writing.
You are free to define your own roles.
It is allowed to set an empty value or to omit the role.

Some roles are defined for technical reasons:



If you adhere to the process outlined by Niklas Luhmann, a zettel could have one of the following three roles:



However, you are free to define additional roles, e.g. `material` for literature that is web-based only, `slide` for presentation slides, `paper` for the text of a scientific paper, `project` to define a project, ...