IDL collates information on deaths at age 105+ from countries with reliable civil registry or equivalent systems. To ensure completeness, data collection relies on sources that systematically include all deaths that occur within a population or territory. This avoids any information bias that could result from any interdependence between the probability of an individual being included in the database and the exceptional age to which they have lived, as would occur if the database only included the very old individuals reported in the press and other media. The deaths collected in this way are then subjected to a strict age validation procedure. The recommended procedure involves verifying that the identity and birth information contained in the death certificate match those appearing on the birth certificate. However, this procedure does vary between countries (see metadata sheets). Validation may mean that certain deaths are wrongly excluded if age cannot be validated or invalidated...