SQL Server中嵌套事务的隔离范围是什么？

Consider the following SQL:

考虑以下SQL:

BEGIN TRAN
SET TRANSACTION ISOLATION LEVEL READ COMMITTED

INSERT Bands
    (  Name  )
SELECT 'Depeche Mode'
UNION
SELECT 'Arcade Fire'

    -- I've indented the inner transaction to make it clearer.

    BEGIN TRAN
    SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

    SELECT *
      FROM Bands

    COMMIT

-- What is the isolation level right here?

UPDATE Bands
   SET Name = 'Modest Mouse'
 WHERE Name = 'Oddest House'

COMMIT
BEGIN