What is an element function?

[edgarogh]

On the docs about "element functions":

Some functions are associated with elements like headings or tables. When called, these create an element of their respective kind. In contrast to normal functions, they can further be used in set rules, show rules, and selectors.

This tells us what "element functions" do (return elements + can be used in some places where other functions can't), but not what they are, i.e. what makes them element function intrinsically. There is nothing explaining what an "element" is (and the concept seems tightly coupled with functions anyway).

• What makes a content value an "element"?
• Are "elements" reserved for built-in functions?
• Is there a way to define "elements" in user code?

Thanks in advance and thank you for this amazing piece of software!

[TabError]

I have exactly the same questions. I want to generate outlines for some custom "elements"(?) and am currently looking into selectors. The word 'element' is all over the place but not explained anywhere.
(I'm sure I'll find a way to get the outline I want with the existing features and without understanding elements. Nevertheless I'd like to understand)

https://typst.app/docs/reference/foundations/selector/

[TabError]

I just found this this discussion: #2681
and thus this issue: #147

[TabError]

Which means: They are not implemented for custom use yet. And just yesterday the dev stated that work has not begun.

[TabError]

There is this blog entry from the developer too, which explains somehow what elements are supposed to be.

https://laurmaedje.github.io/posts/types-and-context/