\normalsfcodes
This command should be used to restore the normal settings of the parameters that affect spacing between words, sentences, etc.
An important use of this feature is to correct a problem, reported by
Donald Arseneau, that punctuation in page headers has always (in all
known TEX formats) been potentially wrong whenever a page break
happens while a local setting of the space codes is in effect. These
space codes are changed by, for example, the command
verb|
frenchspacing|) and the verbatim environment.
It is normally given the correct definition automatically in
\begin{document}
and so need not be explicitly set; however, if it
is explicitly made nonempty in a class file then automatic
default setting will be over-ridden.