Understanding Work Items mapping file

We are importing work items from bugzilla and need a little clarification on the mapping file.

For example, the severity mapping looks like:
<attribute>
<attributeType>
<value>
<value>
<value>
<value>
<value>
<value><Unused>
<value><Unused>
<value><Unused>
<value><Unused>
<value><Unused>
<value><Unused>
<value><Unused>
</attributeType>

I am guessing that "severity.literal.l6" is refering to one of the values in the severity enumeration. But I am not sure how to map it.

When I look at the values in the severity field in Jazz I see the display names for the severity values.