Now suppose that you want myfont10 to be magnified, say to magstep 1 (magnified by 1.2), for a `jumbo' printer. Assuming that the local/modes file has a mode for the jumbo printer, you may then run with the following three commands:
\mode=jumbo; mag=magstep(1); input myfont10to produce `myfile10.tfm' (again!) and a GF font, `myfile10.360gf'. On MS-DOS, the file names will be truncated; for example, `myfile10.360'.
The `360' is `300 * 1.2', indicating the magnification. A 360 dpi font can be used either as a magnification 1.2 font on a 300 dpi printer or as a normal sized font on a 360 dpi printer.
Note, however, that the language includes special hints for each output device which clue as to the reactions of the output device to pixel-sized minuscule changes.
So for highest quality, you would not even want to mix the fonts for two 300 dpi printers, unless they share the same mode and most probably the same print engine.