Similar-origin window agent definition (un)clarity

[gterzian]

from https://html.spec.whatwg.org/#similar-origin-window-agent

An agent whose [[CanBlock]] is false and whose set of realms consists of all realms of all same-agent Window objects.

Either the wording is unclear, or I'm missing something. Specifically, what is meant with " all realms of all same-agent Window objects"?

Could it be that what is in fact meant is more clearly expressed as:

An agent whose [[CanBlock]] is false and whose set of realms all consist of same-agent Window objects.

[annevk]

No, a Window object is not a realm. It's 1:1 with a realm, but they're not the same.

[gterzian]

Ok, I was going to write that the current wording makes it sounds like a global grouping of all "same-agent Window objects" across the entire user-agent, and then I realized that's exactly what it is, since all "same-agent Window objects" will necessarily be part of the same "similar origin window agent", unlike mere "same-origin" ones, which could be part of different groups...

[gterzian]

One last question, which I'll keep in here for convenience and since it's related:

In the note just above that reads:

All same-agent Window objects together represent a group of Window objects that can synchronously access each other, though sometimes only after setting the document.domain attribute (in)appropriately.

Why mention a group of Window objects without further definition? Isn't such a group in fact a "Similar-origin window agent"? Could linking the note to definition make it more relevant?

[annevk]

Well, we're using the grouping concept to define the agent concept. This will be revamped as per #4361 though.