> When the [kbd](https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-kbd-element) element is nested inside a [samp](https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-samp-element) element, it represents the input as it was echoed by the system.

[skillenj79]

When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system.

When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item.

When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-kbd-element

Basically semantics wankery, and maybe we should change it...

Originally posted by @zcorpan in whatwg/html#7672 (comment)