The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog | 
|---|---|---|---|
| tidy.default_config | "" | PHP_INI_SYSTEM | |
| tidy.clean_output | "0" | PHP_INI_USER | 
Here's a short explanation of the configuration directives.
tidy.default_config
     string
    Default path for tidy config file.
tidy.clean_output
     bool
    Turns on/off the output repairing by Tidy.
       Do not turn on tidy.clean_output if you are generating
       non-html content such as dynamic images.