see https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state -> U+003F QUESTION MARK (?) Set the [temporary buffer](https://html.spec.whatwg.org/multipage/parsing.html#temporary-buffer) to the empty string. Switch to the [processing instruction open state](https://html.spec.whatwg.org/multipage/parsing.html#processing-instruction-open-state).
see https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state -> U+003F QUESTION MARK (?)
Set the temporary buffer to the empty string. Switch to the processing instruction open state.