optional, single

—

Specifies the argon fraction of a (breathing) gas, given as a real number less or equal 1.0 in percent (of volume).

<mix>

—

<h2>, <he>, <mix>, <n2>, <o2>

<-- 100 % Argon -->
<ar>1.0</ar>
                

<-- 73 % Argon -->
<ar>0.73</ar>