Whitespace characters include the space and newline characters. (Implementations may provide additional whitespace characters such as tab or page break.)
However, §7.1.1 has:
⟨intraline whitespace⟩ → ⟨space or tab⟩ ⟨whitespace⟩ → ⟨intraline whitespace⟩ | ⟨newline⟩ | ⟨return⟩
So §2.2 implies that supporting tabs is allowed but not required, yet §7.1.1 implies supporting tabs is required.
I don't have access to my suite of Schemes today, so I can't verify the state of the art.