   (latex-unicode-math-mode-update-rules))
 
 (defgroup latex-unicode-math nil
-  "LaTeX Unicode math symbols"
+  "LaTeX Unicode math symbols
+Invert (see `latex-unicode-math-invert-region') only works with
+replacements where the right-hand side is a single letter, not a
+one-letter string.  So it is recommended to use one-letter
+strings instead of characters for one-way replacements, where
+invert wouldn't make sense."
   :prefix "latex-unicode-math-"
   :group 'tex)
 

  '(("\\gets " "← ")
    ("<-" "←")
    ("\\leftarrow" ?←)

    ("<--" "⟵")
    ("\\longleftarrow" ?⟵)

    ("\\to " "→ ")
    ("->" "→")
    ("\\rightarrow" ?→)

    ("-->" "⟶")
    ("\\longrightarrow" ?⟶)

    ("<->" "↔")
    ("\\leftrightarrow" ?↔)

    ("<-->" "⟷")
    ("\\longleftrightarrow" ?⟷)

    ("=>" "⇒")
    ("\\Rightarrow" ?⇒)

    ("==>" "⟹")
    ("\\Longrightarrow" ?⟹)

    ("<=>" "⇔")
    ("\\Leftrightarrow" ?⇔)

    ("<==>" "⟺")
    ("\\Longleftrightarrow" "⟺")
    ("\\iff" ?⟺)

    ("\\mapsto" ?↦)
    )
  "Arrows for `latex-unicode-math-mode'."
  :type '(repeat (list :tag "Rule"
                       (string :tag "Input")


(defcustom latex-unicode-math-mode-rules-extra
  nil
  "Extra rules for `latex-unicode-math-mode'.
Please add your own rules here."
  :type '(repeat (list :tag "Rule"
                       (string :tag "Input")
                       (choice :tag "Output" string character)))
