Acceptability Criteria
  1. Complete Inhalation
  2. Good Start
     iNo Excessive Hesitation or Low PEF
     iExtrapolated Volume (EV) < 5% of
          the FVC or 0.15 liters
     iNo Cough (during the first second)
3. Maximal Effort Throughout
    iNo Variable Effort
    iNo Obstruction of the Mouthpiece
4. Complete Exhalation
    iOne-second Plateau in V-T Curve
    iAt Least 6-seconds of Exhalation
    iNo Abrupt Termination

Repeatability Criteria
  Two Largest FVCs Within 0.15 L
  Two Largest FEV1 Within 0.15 L