[R] what's the meaning of these in R-lang?

[ronggui]

In this case the environment contains the variables local to the function, and its enclosure is the environment of the enclosing function.(R-lang:p11)

I want to know if the "enclosing function" means the closure of the function? for example ,if I call function mean(),and the create an environment,say e1,then the enclosure of e1 is the namespace of base package? Right?

Thank you!