-that ``noun`` in the grammar which implies that the action needs a direct
-object) that something is missing, so it issues a helpful prompt. In the
-second, the player mentions an object that isn't in scope (in fact, there's
-no dog anywhere in the game, but the interpreter isn't about to give *that*
-away to the player). In the third, the object is in scope, but its
-``before`` property intercepts the ``Untie`` action (and indeed, since this
-object is of the class ``Prop``, all actions apart from ``Examine``) to
-display a customised rejection message. Finally, the fourth usage refers
-to an object which *doesn't* intercept the action, so the interpreter calls
-the default action handler -- ``UntieSub`` -- which displays a
-general-purpose refusal to perform the action.
+that :var:`noun` in the grammar which implies that the action needs a
+direct object) that something is missing, so it issues a helpful prompt.
+In the second, the player mentions an object that isn't in scope (in fact,
+there's no dog anywhere in the game, but the interpreter isn't about to
+give *that* away to the player). In the third, the object is in scope, but
+its :prop:`before` property intercepts the :act:`Untie` action (and indeed,
+since this object is of the class ``Prop``, all actions apart from
+:act:`Examine`) to display a customised rejection message. Finally, the
+fourth usage refers to an object which *doesn't* intercept the action, so
+the interpreter calls the default action handler -- ``UntieSub`` -- which
+displays a general-purpose refusal to perform the action.