绑定中的WPF FindAncestor

FindAncestor有一点让我很困惑，请看下面的示例：

<Expander.HeaderTemplate>
    <DataTemplate>
        <StackPanel Orientation="Horizontal">
            <Label Name="headerLabel"  Content="Show Contents" Padding="0" VerticalAlignment="Center" />
            <Button Name="headerButton" Margin="6,0,0,0" Content="Button" Padding="6,1" />
        </StackPanel>
        <DataTemplate.Triggers>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Expander}}, Path=IsExpanded}" Value="True">
                <Setter TargetName="headerLabel" Property="Content" Value="Hide Contents" />
            </DataTrigger>
        </DataTemplate.Triggers>
    </DataTemplate>
</Expander.HeaderTemplate>

我看到了这三个方面的很多例子，这只是个人品味的问题吗

来自：

如果这个属性是 未显式设置，设置AncestorType或AncestorType并 AncestorLevel属性将隐式锁定此属性值 找到舞蹈家

Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Expander}}, Path=IsExpanded}"

Binding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Expander}}, Path=IsExpanded}" 

Binding="{Binding RelativeSource={RelativeSource AncestorType={x:Type Expander}}, Path=IsExpanded}"