Meaning of FEV/PEF Peak Flow Meter

A friend of mine gave me a new Piko-1 Peak Flow Digital read out meter but it has no directions with it.
Can anyone tell me what the letters FEV and PEF stand for and what their meaning is...it also has a Green/Yellow/Red zone on it. Thank You.

[National Jewish]

A peak flow meter is a small, hand-held device that gives a number that measures how fast you can blow out air after you have taken in as deep a breath as possible.  This number shows how well your lungs are working.  This number is the PEF (peak expiratory flow).  The FEV (forced expiratory volume) probably has a small number one after it and refers to the amount of air blown out in the first second.  It is the number most commonly monitored in asthmatics.  It measures the amount of obstruction.  The color zones are set for each individual and help monitor the level of obstruction.  You should contact the company that manufactures the Piko device and request directions (the package insert).  Sometimes peak flow numbers will drop up to a day before asthma symptoms start.  Checking your peak flow number could help you to know whether what you are feeling is a symptom of your asthma.  Your peak flow number should increase 20 to 30 minutes after using a rescue inhaler.  Please read our Peak Flow Monitoring MedFact at http://www.nationaljewish.org/medfacts/peak.html for further information.