DITA2Go produces an index for print RTF output based on the <indexterm> elements in your DITA document. However, the index will not be hyperlinked in Word.
To specify the number of columns in the index:
[Index] ; IndexColumns = column count for index; default 2, max 4. IndexColumns = 2
The default is a two-column index.
To specify a leader between index entry and page number:
[Index] ; IndexLeader = one of: none, space, dot (default), or line. IndexLeader = dot
IndexLeader=space puts a right tab between each term and its page number; IndexLeader=dot inserts a dot leader; and IndexLeader=line inserts an underline. The default is a row of dots.
To insert a divider between letter groups:
[Index] ; IndexStyle = one of: none, space, or letter (default). IndexStyle = letter
IndexStyle=space puts a space before each new index group when the first letter of the term changes; IndexStyle=letter puts the actual letter there; IndexStyle=none keeps the index entries all together without any division between letter groups. The default is to insert a letter. To format that letter, use the format name that Word uses, index heading; all lowercase, one space between index and heading.
This is what you get with the default values:
{\f0\fs22\uld INDEX \\e "\tab " \\h "A" \\c "2" \\z "1033" }}
The last item, 1033, is the language; DITA2Go uses the same language setting for the entire output file.