What does invoke mean?

[annevk]

Often the API section talks about invoking or matching a production without defining what that means.

E.g. "Invoke set-host on the input with url as url." but then https://specs.webplatform.org/url/webspecs/develop/#set-host only seems to take a single input argument so where is url coming from? And how does one invoke a diagram or get a return value from it? We'd need to explain that in terms of first principles.

[domenic]

+1; somewhat related to #5.

It seems like the main problem is in the setters section.

[annevk]

Well, "invoke" in general doesn't mean much when applied to a diagram. Is that defined to mean something somewhere? If so, we should link it.