[chuck-users] Very Basic Question

On several ugens, I see both a phase parameter and a phase offset parameter. What exactly do these mean and how would one use them. For instance, on the sndbuff ugen: • .phase - ( float , READ/WRITE ) - set/get phase position ( 0-1 ) • .phaseOffset - ( float , READ/WRITE ) - set/get a phase offset Thanx much... -- Rich