@@ -187,26 +187,26 @@
     ◊say["Tavi"]{You also write fiction, or you used to. Do you still?}
     ◊say["Lorde"]{The thing is, when I write now, it comes out as songs.}
   }
 }|
 
-@defproc[(index [heading string?] [elements xexpr?] ...) txexpr?]
+@defproc[(index [#:key key string? ""] [elements xexpr?] ...) txexpr?]
 
-Creates an entry in the keyword index under @racket[_heading] that points back to this spot in the
-document. If @racket[_elements] is not empty, the web edition of the document will use it as the
-contents of an understated hyperlink to back to @racket[_heading] in the keyword index.
+Creates a bidirectional link between this spot in the document and an entry in the keyword index
+under @racket[_key]. If @racket[_key] is not supplied, the string contents of @racket[_elements] are
+used as the key.
 
 The example below will create two index entries, one under the heading “compassion” and one under
 the heading “cats”:
 
 @codeblock|{
   #lang pollen
 
   “I have a theory which I suspect is rather immoral,” Smiley 
   went on, more lightly. “Each of us has only a quantum of 
-  ◊index["compassion"]{compassion}. That if we lavish our concern
-  on every stray ◊index["cats"] cat we never get to the centre of 
+  ◊index{compassion}. That if we lavish our concern on every
+  stray ◊index[#:key "cats"]{cat} we never get to the centre of 
   things. What do you think of it?” 
 }|
 
 @defproc[(note [#:date date-str non-empty-string?]
                [#:author author string? ""]