to_xml node names with underscores

When I call to_xml on my active record objects, it replaces
underscores with hypens. E.g.:

<categories>
  <category>
<content-provider-id type="integer">1</content-provider-id>
<id type="integer">2</id>
<name>Traffic Alerts</name>
</category>
</categories>

When the actual field is content_provider_id. I remember seeing an
option for this somewhere... Any ideas?

http://api.rubyonrails.com/classes/ActiveRecord/XmlSerialization.html

Found it. What's the point of dasherizing anyways?