Try setting the sparse property to .f.

>In grid.col.txt.valid I update the field of the underlying alias/table based on the value of another field in the same row. However I find that when I move up or down in this column or just move using cursor keys this columns value is updated for all rows with the value which should be updated only for the current row. Most cases this happens when I move from/to the first row of the ...snip