>>1
facepalm.jpg
First of all, you forgot the XML prolog:
<?xml version="1.0" encoding="UTF-8"?>
Second, your document is in the null namespace, which is discouraged. And finally, you should provide a schema, preferably as XML Schema, although a DOCTYPE is OK as well.
Here is the corrected version of your XML instance document.
<?xml version="1.0" encoding="UTF-8"?>
<message
xmlns="urn:anonymous:4chan:dis:prog"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:anonymous:4chan:dis:prog message.xsd">
<acronym>ITT</acroynm>
<subject>we</subject>
<verb>speak</verb>
<object>
<acronym>XML</acronym>
</object>
</message>
message.xsd
---------------
<xs:schema
xmlns:tns="urn:anonymous:4chan:dis:prog"
targetNamespace="urn:anonymous:4chan:dis:prog">
<xs:element name="message">
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:acronym"/>
<xs:element name="subject" type="xs:string"/>
<xs:element name="verb" type="xs:string"/>
<xs:element name="object"/>
<xs:complexType>
<xs:sequence>
<xs:element ref="tns:acronym"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="acronym" type="xs:string"/>
</xs:schema>