/usr/lib/openoffice/share/registry/modules/org/openoffice/Setup/Setup-calc.xcu

<node oor:name="com.sun.star.sheet.SpreadsheetDocument" oor:op="replace">
  <prop oor:name="ooSetupFactoryDefaultFilter">
   <!-- <value>calc8</value> --> 
   <value>MS Excel 97</value>
  </prop>
</node>