what does `plugin` mean?

[sunt05]

For the code here:

checkout/action.yml

Lines 21 to 22 in 7f0669c

	runs:
	plugin: 'checkout'

What does plugin mean?

I cannot find any reference on the help page.

[dougnukem]

I'm curious about this one, is it referencing some built-in native action commands or something?

[TingluoHuang]

it's a built-in action, we plan to make it as a javascript action so everyone can see how it work. 😄

[sunt05]

Thanks for the explanation! @TingluoHuang
Any reference for the js-based actions?