>>>>
>>>>You welcome. Make sure you don't have NULL values in the field.
>>>
>>>I won't have NULL values but what got me a little concerned is what Borislav said about optimization. I am thinking that maybe I should have another index tag on this field, just for optimizing queries. Does it make sense?
>>
>>Rushmore doesn't use indexes with For clause.
>
>I understand now. But what if I have two index tags for the same field: one with the FOR clause and another one, without. So one will be used to enforce my business rule and another for queries. Does this make sense?

Absolutely.