An Info Index link that can be reached via ^X^E

Question

https://www.gnu.org/software/emacs/manual/html_node/emacs/Unibyte-Mode.html
corresponds to
(info "(emacs) Unibyte Mode")^X^E

So what does
https://www.gnu.org/software/emacs/manual/html_node/emacs/Unibyte-Mode.html#index-GTK-input-methods
correspond to? Not
(Info-index "GTK input methods")^X^E
Which blows up (triggers backtrace). So then what does it equal, that I can use ^X^E on, and end up in the same spot?

Answer 1

Try

(progn
  (info "(emacs)")
  (Info-index "GTK input methods"))

Info-index looks in the index of the current manual, so you have to establish that manual first.