default

Returns default value. If the default value does not exist, this method returns nil.

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Workbook')
method = WIN32OLE_METHOD.new(tobj, 'SaveAs')
method.params.each do |param|
  if param.default
    puts "#{param.name} (= #{param.default})"
  else
    puts "#{param}"
  end
end

The above script result is following:
    Filename
    FileFormat
    Password
    WriteResPassword
    ReadOnlyRecommended
    CreateBackup
    AccessMode (= 1)
    ConflictResolution
    AddToMru
    TextCodepage
    TextVisualLayout