442 ong>Someong> ong>Commentsong> onPhilatelicLatinSquaresfromPakistan many sizes, including size 5 × 5 using the gerechte design GD1 (Figure 4.2, left panel), which Maack calls “cross”, see Figures 4.2 (left panel) and 4.3 (left panel). Maack  gives 240 Sudoku puzzles and solutions of size 5 × 5, but none of the solutions are in standard-form: 1,2,3,4,5 in sequence in the top row. The gerechte designs used by Think- Fun for 5 × 5 Sudoku puzzles differ from those used by Maack, see Figure 4.3 (centre and right panels): in these examples there is no central “cross” region and the regions all have different shapes. In the second ThinkFun example (Figure 4.3, right panel), one region is an entire column: the centre column. The PLS fromPakistan shown in Figure 4.1 is the only PLS (from any country) that we have found of type KV2, and we have found just one PLS (from any country) of type KV1 (Figure 4.4). Depicted are these antique automobiles from the late 19th and (very) early 20th century (from left to right in the first row): (1) 1893 Duryea, (2) 1894 Haynes, (3) 1898 Columbia, (4) 1899 Winton, (5) 1901 White. FIGURE 4.4: USA 1995, Scott 3023v.
Ka Lok Chu et al. 443 5 TWO MORE 5×5 LATIN SQUARES ASSOCIATED WITH POSTAGE STAMPS FROM PAKISTAN Pakistan 2005, Scott 1071: mushrooms 6x5 splits into two 3x5, each FIGURE subset of 5x5 5.1: Pakistan 2005, Scott 1071.