The behaviour of these functions is affected by settings in php.ini.
Here's a short explanation of the configuration directives.
htscanner.config_file
Filename to use as configuration file.
htscanner.default_docroot
Default document root.
htscanner.default_ttl
Cache time out for the configuration data, in seconds.
htscanner.stop_on_error
Stop on error (parse error, cannot set an ini setting).