Via <setdcallgasdefinitions/> all breathing gas definitions (see <gasdefinitions>) are transferred to the dive computer.
(see also <setdcdata>)
<divecomputercontrol>
    <setdcdata>
        <setdcgasdefinitionsdata>
            <!-- send all defined breathing gases to the dive computer -->
            <setdcallgasdefinitions/>
        </setdcgasdefinitionsdata>
    </setdcdata>
</divecomputercontrol>