From Atsushi Toyokura in pkgsrc-wip
Japanese pLaTeX/upLaTeX formats and packages often conflict
with other LaTeX packages which are unaware of pLaTeX/upLaTeX.
In the worst case, such packages throw a fatal error or end up
with a wrong output. The goal of this package is that there
should be no need to worry about such incompatibilities,
because specific patches are loaded automatically whenever
necessary. This helps not only to simplify source files, but
also to make the appearance of working pLaTeX/upLaTeX sources
similar to those of ordinary LaTeX ones. This package depends
on the filehook package written by Martin Scharrer.
