Ambiguity between mintable and invokable capabilities

[Latrasis]

Reading the current draft from docs/Usage.md, it's not clear to me how the user can clearly know which capability needs to be minted or invoked.

For example, when I see this:

let &cap2 = mint(&cap1, param)
let ret = invoke(&cap2,"data")

It's not clear when cap1 can be used to invoke or mint something. What happens if I invoke(&cap1, "data") ?