G.2.2 Replacements with other argument
%[format]?[argument] special texts
Apart from different representations of the actual system time, a fixed format
date text can be created. Moreover, it is possible to produce a day number,
which bears the Julian date as base date and which can be deferred if needed.
Furthermore, the approximate distance and the course angle between two
geographic point locations, and different Sun and Moon oriented data and times
for at pleasure any geographical location can be created. It is also possible
to display the contents of environment variables in the fixed date text.
For the argument these
special texts may have, no special rules concerning definite omission
values are valid.