cookbook's filter envelope

[cinephos]

If I understand correctly Env.adsr(0.3, 0.3, 0.9, 1.2) sig = RLPF.ar( in: LFSaw.ar(220), freq: 220 + (220 * env), rq: 0.005 ); You consider the cutoff frequency as the starting or zero point of the envelope, and an octave higher the peak or 1.0 point of the filter envelope. sustain cut off frequency is 220 + (220 * 0.9) = 418 Is his correct?

I ask myself, if this is the intended way in Welsh's book...