Does a buffer system have to have H+ dissassoc, or can it be O's instead?

[jenzao]

Does a buffer system have to have H+ dissassoc, or can it be O's instead?
for eg, HSO4- --> HSO3-
is this a buffer?

 

[symbolipoint]

What does your book and what does your teacher tell you about a buffer system? Something about weak acid and its conjugate base, or weak base and its conjugate acid..., weak acid and salt of the weak acid, or weak base and salt of the weak base,...