>>>When I try to append a blank to a table with an index, I am confronted with
>>>this message: Uniqueness of index "thisindex" is violated.
>>>I never got this till now, Has anyone seen it?
>>
>>Frequently. :-) Your index is either candidate or primary, and you already have another blank in the table.
>
>Right I was adding another blank, but so what I say in other versions of fox.
>why /how is this uniquness being enforced?

As I said above, you are using either a Primary or Candidate index. This type of index enforces unique values, unlike Unique, which merely has one index entry per value in the table.