Some parts of the Netherlands, especially Zeeland, suffered heavy record loss during World War II. Church records and court records may have been lost as a result. Most civil registration records survive, because duplicates were made of those at the time of creation, and both copies were in different locations.
Before World War II, some people created transcriptions or indexes for their own use. These derivative sources may survive even if the original records were lost. Archives have been collecting these indexes and transcriptions to fill in the gaps in their collections.
The transcriptions made by researcher Hollestelle of the church records of Tholen are a great example. They have been scanned and indexed and are now available on the Archief Tholen website. Using them in combination with surviving orphan chamber and court records allows us to trace ancestors back even though many church records are gone.
See also the article How to Find out What Church Records Survive.