The definition of focus is not specified here

[k7z45]

In chapter 12. Elements, section 12.4 Interaction:

focus

How is focus defined, is it document.activeDocument == target element of send keys?
Say if we have a content editable body element, according to https://developer.mozilla.org/en-US/docs/Web/API/DocumentOrShadowRoot/activeElement, "When there is no selection, the active element is the page's 'body' or null.". If the activeDocument is the body element, should we consider this a focus? From user's perspective, it may be more reasonable to treat this as not focus, then we will need to move the caret to the end.