Examples
Example 1
This example is as simple as you can get. The first to win 2 matches, wins the round.
<format best-of="3">
    <match>Facility TE</match>
    <match>Ascendance</match>
    <match>Limbo II</match>
</format>
Example 2
This example is a simple best-of-3 with a veto system.
<format best-of="3">
    <veto>
        <decider>
            <match id="veto-decider">No Return</match>
        </decider>
        <options>
            <match>Ascendance 02</match>
            <match>Facility TE</match>
            <match>Nartica</match>
            <match>Desert Sanctuary</match>
            <match>Smoke</match>
        </options>
        <order ban-until="3" starting-team="2" />
    </veto>
</format>
Example 3
This example is more complicated. This is a best-of-3 of gamemodes. Each gamemode constitutes a round, and every round is a best-of-1 (that means that winning one match of that gamemode will give you a round) with the exception of Conquest, where you will need to win 2 matches to win the round.
<format best-of="1">
    <veto>
        <decider>
            <match id="veto-decider">No Return</match>
        </decider>
        <options>
            <format name="CTW" best-of="3">
                <veto>
                    <decider>
                        <result-from id="veto-decider" />
                    </decider>
                    <options>
                        <match>Race for Victory 2</match>
                        <match>Fairy Tales 2: A Tale or Two</match>
                        <match>Golden Drought III</match>
                        <match>Deepwind Jungle TE</match>
                        <match>NextGen TE</match>
                    </options>
                    <order ban-until="1" starting-team="2" />
                </veto>
            </format>
            <format name="DTM" best-of="3">
                <veto>
                    <decider>
                        <result-from id="veto-decider" />
                    </decider>
                    <options>
                        <match>Warlock</match>
                        <match>Spaceship Battles TE</match>
                        <match>The Fenland</match>
                        <match>Ender Blast</match>
                        <match>BoomBox</match>
                    </options>
                    <order ban-until="1" starting-team="2" />
                </veto>
            </format>
            <format name="Conquest" best-of="3">
                <veto>
                    <decider>
                        <result-from id="veto-decider" />
                    </decider>
                    <options>
                        <match>Limbo II</match>
                        <match>Facility TE</match>
                        <match>Dwyer Hill</match>
                        <match>Nartica</match>
                        <match>Desert Sanctuary</match>
                    </options>
                    <order ban-until="3" starting-team="2" />
                </veto>
            </format>
        </options>
        <order ban-until="1" starting-team="2" />
    </veto>
</format>