sentences:  The numbering system is based first on "global quadrant" numbers where 1=NE, 3=SE, 5=SW, 7=NW which gives the initial digit of any square code (1xxx, 3xxx, 5xxx, 7xxx).The second digit (x0xx through x8xx) indicates the number of tens of degrees latitude (north in global quadrants 1 and 7, south in global quadrants 3 and 5) of the 'minimum' square boundary (nearest to the Equator), i.e.a cell extending between 10°N and 20°N (or 10°S and 20°S) has this digit = 1, a cell extending between 20°N and 30°N has this digit = 2, etc.