%%% (Ir)relevant missing character message

Try out the code

\beginverbatim
\hsize=7.3in \vsize=9.8in
\leftskip=30mm \rightskip=30mm \parindent=1em

\font\LOGO=logo10
\def\MP{{\LOGO METAPOST}}
\def\MF{{\LOGO METAFONT}}

short \TeX, \MF\ or \MP\ macro/macros (half A4 page or half a~screen at most)[...]
\endverbatim

The output is typeset without breaking any word at the end of line. Try to 
explain why then the log file contains the line

\beginverbatim
Missing character: There is no - (45) in font logo10!
\endverbatim

While breaking paragraphs into lines \TeX\ checks all feasible breakpoints
and chooses the one of the smallest sum of costs (see \TeXbook, chapter 14).
The message in the log file informs that some of the considered ways of
typesetting the paragraph had a discretionary break after {\tt META}.

\endinput
