>> The actual numbers returned under various conditions add only more >> confusion. >> >> $ groff -Tascii <<< '.tm \n(.V' > /dev/null >> 40 >> $ groff -Tps <<< '.tm \n(.V' > /dev/null >> 1 >> $ groff -Tpdf <<< '.tm \n(.V' > /dev/null >> 1 >> >> I don't see how the vertical resolution of the ascii device can be >> 40 times that of the ps and pdf devices. > > It's the opposite. A ps driver has 40 times larger resolution than > the ASCII device.
Oops, this is wrong, sorry, see below. I agree that the explanation of \n[.H] and \n[.V] is a bit sparse. For ASCII, groff uses 240 horizontal units per inch (see below). However, everything gets rounded to a multiple of \n[.H] (which is 40). As a corollary, the PS driver's horizontal resolution is 7200 times larger than the ASCII device. .nr foo 1i .tm \n[foo] gives 240 for -Tascii and 72000 for -Tps. Both values must be divided by the output driver's \n[.H] value, yielding the above ratio. Werner