If the large difference in Q values persists, it should be interpreted to mean that something
has happened to the spectrophotometer so that the Table of Settings of Q used with the instrument
is no longer valid. If the problem persists, steps must be taken to correct the Table of Settings of Q
in order to ensure that future ozone observations are made on correct wavelengths. Instructions
for correcting an erroneous Q setting table are given in Annex B.