Systems within ATCF are identified with the basin prefix (AL – North Atlantic Ocean, CP – Central North Pacific Ocean, EP – North-East Pacific Ocean, IO – North Indian Ocean, SH – Southern Hemisphere, SL – South Atlantic Ocean, WP – North-West Pacific Ocean) and then followed by two digit number between 01 and 49 for active tropical cyclones,<ref name="Navy">{{cite web|url=httphttps://wwwscience.nrlmry.navy.mil/atcf_webatcf/docs/database/new/abrdeck.html|title=Best Track/Objective Aid/Wind Radii Format|date=2010-06-08|access-date=2014-06-20|author=[[United States Naval Research Laboratory]]–[[Monterey, California|Monterey]], Marine Meteorology Division|publisher=[[United States Navy]]|archive-date=2017-11-06|archive-url=https://web.archive.org/web/20171106132459/https://www.nrlmry.navy.mil/atcf_web/docs/database/new/abrdeck.html|url-status=deadlive}}</ref> which becomes incremented with each new system, and then the year associated with the system (e.g. EP202015 for [[Hurricane Patricia]]). Numbers from 50 through 79 after the basin acronym are used internally by the basin's respective Tropical Cyclone Warning Centers and [[Regional Specialized Meteorological Center]].<ref>{{cite web|url=http://www.ofcm.gov/homepage/text/spc_proj/ihc/action-items.pdf|page=14|date=2007|access-date=2014-05-20|title=61st Interdepartmental Hurricane Conference Action Items|author=Office of the Federal Coordinator for Meteorology|publisher=Internet Archive Wayback Machine|url-status=dead|archive-url=https://web.archive.org/web/20071129132837/http://www.ofcm.gov/homepage/text/spc_proj/ihc/action-items.pdf|archive-date=November 29, 2007}}</ref> Numbers in the 80s are used for training purposes and can be reused. Numbers in the 90s are used for areas of interest,<ref name="ATCF Readme">{{cite web|author=Michael J. Brennan, [[National Hurricane Center]]|url=http://ftp.nhc.noaa.gov/atcf/README|title=Automated Tropical Cyclone Forecast (ATCF) Data Files / Text Files|publisher=[[National Oceanic and Atmospheric Administration]]|date=2013-05-18}}</ref> sometimes referred to as [[Invest (meteorology)|invests]] or areas of disturbed weather, and are also reused within any particular year. Their status is listed the following ways within the associated data file:
