The paper documents identified in the summary barplot (grey / black bars) come from the Shom archives. This inventory comes mainly from the shom archives, but documents may also have been identified in external archives (seaport archives, National Institute of Geographic and Forest Information, national archives centers, etc.). It is possible that several types of documents concern the same period (ledger(s)/tide gauge charts) and their stage of dematerialisation (scanned or not) are possibly different: refer to the table below to find out. Real-time data and recent data can be downloaded: https://data.shom.fr/donnees/refmar/399/download The inventory of Shom archives is in progress. Possibliy, this list could change in future. When documents are ledgers, the sampling frequency is noted if reported during the inventory.