MediaWiki:Apihelp-options-param-optionvalue
The value for the option specified by $1optionname. When $1optionname is set but $1optionvalue is omitted, the option will be reset to its default value.
The value for the option specified by $1optionname. When $1optionname is set but $1optionvalue is omitted, the option will be reset to its default value.