title_body: What symbols/text to use for index references? An index in a printed book would look like this:
  
  
    Concept A: 5, 17
    Concept B: 25, 41, 83
    ...
  
  
  In an ebook the page numbers would be replaced by hyperlinks. The question is what text/symbols to use for the hyperlinks. One option I thought is to use some sequence of arbitrary symbols:
  
  
    Concept A: *, +
    Concept B: *, +, #
    ...
  
  
  Another option would be to use alphabetic sequences or numbers: 
  
  
    Concept A: a, b
    Concept B: a, b, c
    ...
  
  
  I have two indexes: One is a concepts index, where most entries have only one reference and the maximum number of reference for an entry is three. The other is an authors index, where there are also many entries with only one reference, but there are some with up to thirteen.
  
  For small numbers of references I think the first option looks better. For large numbers the second one. But I'd like to use the same style in both indexes.
  
  Are there any other options that may look better? Is there any standard practice for this?
upvoted_answer: I have created an index for an nonfiction title before (a technical manual), and I think indices do serve a purpose -- and by the way, I created an author index too! 
  
  The key thing is making sure the links themselves are large enough that you can click each separate link and not get the wrong one. You should consider increasing the horizontal space between  entries. Separating things by commas also should help. 
  
  I don't think which character you use really matters -- though I prefer the symbols.  I have used as a label a name of a chapter or section or subsection.