In 1996, the IAEA published the Guidebook to Accompany IAEA Map: World distribution of Uranium Deposits (the ‘Guidebook’). This publication, introduced a descriptive deposit classification that expanded upon the classification used in the OECD/NEA-IAEA Red Book. Experts contributed information on a total of 582 deposits worldwide, and provided summary information on these deposits. A web application was developed and made available to the public in 2004 as the geological UDEPO (Uranium DEPOsit) database. A deposit is included if there is known to be a resource estimate. No commercial or economic implications for extraction are made for deposits. If multiple resource estimates are known, only the largest estimate – generally with the lowest cut-off grade - is included. These resource estimations may conform to contemporary resource reporting standards, but may be historical or, uncommonly, an IAEA estimate and so are given as ranges only. This is particularly the case for unconventional or co- or by-product resources. The resource may or may not have already been partly extracted and the estimate quoted is mostly an original pre-mining estimate. In some cases, only production data is available and is used as a minimum resource estimate. Data is obtained from public sources only and locations are approximate. The map of "World Distribution of Uranium Deposits" shows a snapshot of data from early 2017 . The uranium deposit classification scheme used in UDEPO is explained in detail in “Geological Classification of Uranium Deposits and Description of Selected Examples”. "World Distribution of Uranium Deposits (UDEPO) 2016 Edition” explains the geological aspects of the database.