The External Leading control contains a value that specifies the ideal amount of space that should appear between two rows of text printed using a particular font.
Most dot-matrix printer manufacturers suggest printing device fonts at 6 lines to the inch. The External Leading value should be increased or decreased so that the sum of PixHeight and External Leading meet this guideline.
For the Diconix 150 Plus printer, this value is 2 printer points or 16 master units.