This variable affects whether the runtime sets the width of a printer cell according to the rules from Version 4.3 or from the current version. Version 4.3 (and prior versions) computed the width of a printer cell based on the average width of a selected printer font. The width of a printer cell is currently computed in the same way that cells are computed for the screen, namely by the width of the "0" character. For fixed-width fonts, such as Courier, these values are the same for all characters. For proportional fonts, such as Times New Roman, some characters might be wider than the "0" character.
If the current computation is causing your application to print incorrectly, then setting this variable to 1 (on, true, yes) will use Version 4.3 rules instead. When V43_PRINTER_CELLS is set to the default 0 (off, false, no), then the current rules are in effect.