Ramsay
The signature of major and relative minor is always the same whether in #s or ?s; but in the keys with #s in the plate the signature is only given on the major stave, to indicate that generating upwards is its natural way; and in the keys with ?s the signature is only placed in the minor stave, to indicate that generating downward is the natural way for the minor mode. [Scientific Basis and Build of Music, page 113]
See Also