Which GRANTS are needed on a Sequnce?

Hi all,
I just created a Sequence S for User A.
User B has the USAGE Privilage in Schema A.
I granted SELECT On S TO B.
But this does not seem to be enough to use the Sequcence,
postgres claims:
 [1] ERROR:  S.nextval: you don't have permissions to set sequence S
So I granted ALL ON S TO B
which works fine.
What are the minimal grants neeeded? (And where is it documented,
the reference of 7.3.3 sais nothing about Sequences)

Cheers,
Dani