A reference to the XSLT parser.
This parameter is either a boolean value
which toggles logging on and off, or a string containing
the logfile in which log errors too.
This function allows you to set the file in which
you want XSLT log messages to, XSLT log messages are different
than error messages, in that log messages are not actually
error messages but rather messages related to the state of the
XSLT processor. They are useful for debugging XSLT, when
something goes wrong.
By default logging is disabled, in order to enable
logging you must first call
xslt_set_log()
with a boolean parameter which enables logging, then if you
want to set the log file to debug to, you must then pass it a
string containing the filename: