How does the Android layout XML file add comments?

The XML layout file was added with comments and the error content is as follows:

Read the syntax rules for adding comments to XML online:

Annotations in XML

The syntax for writing comments in XML is similar to the syntax of HTML:

<!--this is a comment-->

is not a problem with the annotation itself.

So it may be that the XML in Android has special rules, continue to search found that a netizen said:

XML in Android can be added only after the component layout code, or in front of the component. As shown below:
<relativelayout
android:id= "@+id/item_layout"
android:layout_width= "Fill_parent"
android:layout_height= "Wrap_content"
android:orientation= "vertical" >
<!---->
<linearlayout
android:layout_width= "Fill_parent"
android:layout_height= "Wrap_content"
android:orientation= "vertical" >
<!---->
</LinearLayout>
</RelativeLayout>

Sure enough, then there's no problem ... Otz

How does the Android layout XML file add comments?