Class App.Installer
{

XData setup
{
<Manifest>
  <Default Name="SourceDir" Value="/opt/feeder/src"/>
  <Default Name="Namespace" Value="FEEDER"/>
  <Default Name="Resource" Value="%DB_DEFAULT"/>

  <Namespace Name="${Namespace}" Code="${Namespace}" Data="${Namespace}" Create="yes" Ensemble="1">
    <Configuration>
      <Database Name="${Namespace}" Dir="/voldata/irisdb/feeder" Create="yes" Resource="${Resource}"/>
    </Configuration>

I see the resource is %DB_DEFAUILT with all UPPERCASE.