720 kilometer maps

can someone please give information what a 720 grid line is?
i have downloaded all of the base maps but don't understand what is ment by
start at the 720 kilometer grid line, where do i look for this grid line?

thanks very much jay2004

720 kilometers? That would be 1000 baseboards placed end to end!
Perhaps what is meant is 720 meters. Each baseboard is 720m x 720m. Each grid is 10m square and there are 72 in each direction (north-south and east-west) I'm guessing that the maps are made to align with the baseboards, one map per baseboard.

Ok i see what u mean now. I thank u Very much..... jay2004