The index bloats as records with keys in the index are modified. This bloating only goes away when you reindex or rebuild the indexes. The best practice seems to be to have a table with the index names and expressions and rebuild the indexes from scratch. That's one reason why stonefield database toolkit is so popular.

An analysis of index expressions and relevant code can result in fewer and smaller indexes.

>>>>>When I pack a file - apart from removing references to deleted records - does the index file get optimised in size - or does it get more and more bloated as time goes by?
>>>>
>>>>The indexes get recreated during PACK.
>>>>
>>>>>Is there any way of optimising the size of an index file?
>>>>
>>>>What do you mean?
>>>
>>>Hi Sergey
>>>
>>>Well if I were to create the index file from scratch it would be much smaller - Naomi's suggestion
>>>
>>
>>I'm not sure you have the problem to begin with. Did you experiment and confirm, that PACK ends up with bigger indexes than DELETE TAG ALL, PACK, re-create?
>>
>>I recall it was a problem in VFP8 before SP. Which VFP version you're running?
>
>Sorry - forgot to say - VFP6