Brien,
Just an addendum here, before anyone jumps me...
There is no additional file I/O with setting and clearing the tag. This is because VFP automatically opens or has open the index when the file is opened or the index is created. Sorry.
However, there is additional code overhead. This is demonstrable by replacing
SET ORDER TO < tag name >
SEEK(< expr >)
SET ORDER TO
with
SEEK < expr > ORDER TAG < tag name >
because the latter will be faster.
George
Ubi caritas et amor, deus ibi est