MediaWiki:Apihelp-options-param-change
From British Saws and Saw Makers Updates
List of changes, formatted name=value (e.g. skin=vector). If no value is given (not even an equals sign), e.g., optionname|otheroption|..., the option will be reset to its default value. If any value passed contains the pipe character (|), use the alternative multiple-value separator for correct operation.
