jsguide: Explain more - What is "rectangle rule"?

https://google.github.io/styleguide/jsguide.html#formatting-function-arguments

// If the argument list is longer, wrap at 80. Uses less vertical space,
// but violates the rectangle rule and is thus not recommended.
doSomething(veryDescriptiveArgumentNumberOne, veryDescriptiveArgumentTwo,
tableModelEventHandlerProxy, artichokeDescriptorAdapterIterator) {
// …
}

- Please explain what is "rectangle rule"