Helen:

Thank you for your response.

> I think you'll find the method you want is InvalidateRowNum
> (aRowNum). Pass the IBOQuery's RowNum property as the argument.

Okay--but .RowNum does not exist for a TIBOQuery. There is
TIBOQuery.InternalDataset.RowNum--but will that be synced?

> You don't know (and don't need to
> know) how many rows are in the buffer or (even) how many rows need
> to
> be refetched as the result of a triggering operation. OnCalcFields
> is a row-level event that gets triggered every time a row is fetched
> (or re-fetched) into the row buffer. InvalidateRowNum is just one
> such operation; RefreshXxxx involve others; even scrolling up or
> down the master set may involve invalidation and refetching of rows
> in the buffer.

But if I have a large dataset, and a time consuimg OnCalcFields, I
should be concerned about the number of times it is called. I want the
application to be responsive, not sluggish.