I guess sometimes self-assertions just aren't enough.
<AttributeStatement>
<Attribute Name="urn:blood:type">
<AttributeValue>B-</AttributeValue>
</Attribute>
</AttributeStatement>
When you don't have anything nice to say, well then perhaps its time consider a career as an analyst.
<AttributeStatement>
<Attribute Name="urn:blood:type">
<AttributeValue>B-</AttributeValue>
</Attribute>
</AttributeStatement>