MediaWiki:Api-help-templatedparams

Templated parameters support cases where an API module needs a value for each value of some other parameter. For example, if there were an API module to request fruit, it might have a parameter fruits to specify which fruits are being requested and a templated parameter {fruit}-quantity to specify how many of each fruit to request. An API client that wants 1 apple, 5 bananas, and 20 strawberries could then make a request like fruits=apples|bananas|strawberries&apples-quantity=1&bananas-quantity=5&strawberries-quantity=20.