This is an alphanumeric combination of degrees north and west with a row column index applied to each 1 degree by 1 degree area. TILE - Row and column index to quadrangles. Illinois DNR designation. Rows move north to south and columns west to east. Quad T0101 is USGS 42091-E1.
Values are in decimal degrees.
Q15 - Indicates if arc is also a boundary for a 15 minute quad. 0 - arc is not a 15 min. 0 - arc is not a 7.5 min. DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. DNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose.