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.
The XSLT processor link identifier, created with xslt_create().
This parameter is either a boolean value which toggles logging on and off, or a string containing the logfile in which log errors too.