When reading web page

http://www.saxonica.com/documentation/using-xsl/commandline.html

then there is said about the parameter "-s":
"If the name identifies a directory, all the files in the directory will 
be processed individually."

Does that mean all files just in this directory?
What about files in sub-directories? Are they processed as well?

If not: How can I tell Saxon to process a whole directory tree recursively?

Ben