Positions the cursor on a record relative to the active record in the dataset.
function MoveBy(aDistance : int64) : int64;
Call MoveBy to position the cursor on a record relative to the active record in the dataset.
aDistance indicates the number of records to move. A positive value for aDistance indicates forward
progress through the dataset, while a negative value indicates backward progress.
For example, the following statement moves backward through the dataset by 10 records:
Function returns the actual number of records moved. In most cases, Result is the absolute value
of aDistance, but if MoveBy encounters the beginning-of-file or end-of-file before moving
aDistance records, Result will be less than the absolute value of aDistance.