Can a label only refer to input elements?

Question

W3Schools have this to say about labels:

The tag defines a label for an input element. _{[Emphasis mine]<}

Answer 1

The HTML spec says, about label's "for" attribute, "When present, the value of this attribute must be the same as the value of the id attribute of some other control in the same document. When absent, the label being defined is associated with the element's contents."

So the id references in "for" should be that of a control. What's a control? The spec basically says any input is a control, as is button, select, or object. So Firefox is technically right -- a div is not a control.