Please add the command line option such that when it is specified:

If only one file is specified in the command line (no stylesheet), then to
copy this file through (if it does not embed or refer a stylesheet).

It is useful to not have distinction between these files which embed/refer
a stylesheet and these which do not. It is convenient to process them by
the same "xsltproc" command rather than to get error message about not
specified stylesheet.

Versions of packages xsltproc depends on:
ii  libc6                         2.3.1-16   GNU C Library: Shared
libraries an
ii  libxml2                       2.5.7-1    GNOME XML library
ii  libxslt1                      1.0.30-3   XSLT processing library -
runtime
ii  zlib1g                        1:1.1.4-1  compression library - runtime