In this section all breathing gases, and tanks — as far as concerning settings for a breathing gas consumption calculation — used are described (general data of tanks as parts of the equipment are given in the <tank> section within the <equipment> section). For each breathing gas a separate <mix> subsection has to be created, also a separate <tankdata> subsection for each tank used. <mix>, and <tankdata> are the only elements within <gasdefitions> and can be repeated any times needed. The only rule is that all <mix> subsections have to appear first, thereafter all <tankdata>. This is because within the latter references to breathing gases used are set up. Of course, further references to <tank> elements within the equipment specification (<equipment>) are possible.

<mix>
    <name>
    <o2>
    <n2>
    <he>
    <ar>
    <h2>
    <priceperlitre>
    <maximumpo2>
    <maximumoperationdepth>
    <equivalentairdepth>
<tankdata>
    <mixref/>
    <tankref/>
    <tankvolume>
    <tankpressurebegin>
    <tankpressureend>
    <breathingconsumptionvolume>