Style and templates are sometimes defined directly in the property instead of using a resource, what we call "inlined".

<Button>
  <Button.Template>
    <ControlTemplate TargetType="Button">
      <Border Background="Transparent"/>
    </ControlTemplate>
  </Button.Template>
</Button>

We should clearly specify when the value is default (a default style, with no key and stored by type), versus a value that is inlined.

In the case of inlined values, we should consider also specify when the value is inlined as a Style setter.

<Style TargetType="Button">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="Button">
        <Border Background="Transparent"/>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>