CHQ: SUBJECT: oxygen therapy
  MESSAGE: I have copd and just recieved prescription for oxygen.  It reads like this.....2 L/M nocturnal & w/exertion....I understand the nocturnal but not sure what w/exertion means, I think it is saying to use o2 while exerting my self but do not use o2 under normal conditions, is this correct.
Summary: What does w/exertion mean on a prescription for oxygen?