Tile extents will take a string formed by a comma-separated list of
coordinates. The minimum x is followed by the minimum y, and then the maximum
x is followed by the maximum y value. For example:
minx,miny,maxy,maxy
where minx,miny represent the lower left corner of the
bounding box and maxx,maxy represent the top right corner of the bounding
box.
The tiles that will be read are those whose bounds overlap (not just touch) the specified extents. For example, specifying a Tile Extents of 0,0,10,10 will not read a tile with bounds 5,10..6,11. The entirety of each tile will be read, and therefore features may be read that don't fit into the specified Tile Extents.
If there are no tiles that touch the Tile Extents, then all tiles will be read.