Indicates the — more or less arbitrarily chosen — threshold for the oxygen partial pressure, when the oxygen
fraction of this breathing gas starts to be poisonous. The value is given as a real number, normally it ranges
between 1.4 and 1.7.
Stands inside the <mix> section. If <maximumpo2> is given,
<maximumoperationdepth> must not be given, because
out of the first the maximum operation depth (MOD) can be calculated.