How a user could add their own types

Use the existing syntax and create a new relationship (calling them whatever they want, here I use type)

- [[I looked up today and saw a blue sky]]
	- [[type]] ->
		- [[evidence]]

Side note, since any note can have a relationship, including relationships, you can create interesting layers…

- [[empirical]]
	- <- [[type]]
		- [[evidence]]
        - [[experiment]]

and we can go all sorts of places…

- [[type]]
	- [[type]] ->
		- [[relationship]]

A user might prefer to use a page-property here instead, since

How and when to add restrictive grammar