indexcrafter.pl is intended for use on DocBook SGML or XML index files
that have been automatically or semi‐automatically generated, for
example using the SGML tool collateindex.pl.  indexcrafter.pl modifies
such an index by allowing the addition, deletion, renaming, merging,
nesting and cross‐referencing of index terms.  The operations
performed on the index can be saved to a macro file to be repeated non‐
interactively on additional input files using the same index terms.

The first time indexcrafter.pl is run it will display a numbered list
of index terms.  Use F and P to page through the list if it exceeds
one page.  At any other prompt when asked to select an item by number,
entering letters instead will redisplay the entries that match that
substring.

Choose R, N or M respectively to rename a term, to nest one term
inside another, or to merge two terms together.  S creates a "see"
reference in an empty index entry or a "see also" reference in a
populated one. Choose A to add a blank term (as a container for
nesting others) or D delete a term.  Choose X to export the operations
that you have performed to a macro file, L to load an existing macro
file, and Q to quit.

Subsequent runs of indexcrafter.pl may add the name of the exported
macro file as an argument, in which case the operations recorded in
that file will be performed non‐interactively on the index.  This is
useful if the source document has been edited since the first index
was generated, which may have changed the locations of index terms in
the document.

Download indexcrafter.pl, which is licensed under the GNU GPL, from
http://www.malcolm.id.au/files/software/unix/indexcrafter.pl.