The source node in most cases contains the sample message as written by the developer. If it looks like a dot-delimitted string such as "form.label.firstname", then the developer has not provided a default message.

List (%count%) Lista (%count%) key: headline.list Results (%count%) Wyniki (%count%) key: headline.results Results for "%phrase%" (%count%) Wyniki dla "%phrase%" (%count%) key: headline.results.search