Comment # 21 on bug 942896 from Mindaugas Baranauskas

Seems that these mystic parameters applays only for old fonts, that don't
support unicode.

>From setfont man page:
The correspondence between the glyphs in the font and Unicode values is
described by a Unicode mapping table.  Many fonts have  a  Unicode       
mapping  table included in the font file, and an explicit table can be
indicated using the -u option. The program setfont will load such a       
Unicode mapping table, unless a -u none argument is given. 

Old fonts do not have Unicode mapping info, and in order to handle them there
are direct-to-font maps (also loaded using -m) that  give  a correspondence 
between  user  bytes  and font positions.  The most common correspondence is
the one given in the file trivial (where user byte values are used directly as
font positions).

--

Seems, that some information about using setfont parameters are detailed in
obsoleted mapscrn command. From its man page:

The  mapscrn  command is obsolete - its function is now built-in into setfont. 
However, for backwards compatibility it is still available as a separate
command.

The mapscrn command loads a user defined output character mapping table into
the console driver. The console driver may be later put  into use  user-defined
 mapping  table mode by outputting a special escape sequence to the console
device.  This sequence is <esc>(K for the G0 character set and <esc>)K for the
G1 character set.  When the -o option is given, the old map is saved in
map.orig.