| Absorbed | Unit absorbed another unit and retained the same name |
| Absorbed By | Unit is absorbed by another unit and its name ceases to be used |
| Activated | Unit is raised having previously existed on paper (US Only) |
| Active | Unit was in existence on this date and was already "mobilised" |
| Also Known As | Unit had another designation during the period indicated |
| Amalgamated From | Unit is created by the Amalgamation of other Units |
| Amalgamated Into | Unit is joined with another unit to create an entirely new unit |
| Battle Honour | Official Battle Honour awarded to this unit (British and US units only) |
| Broken Up | Unit is broken up permanently (but not officially disbanded or inactivated) |
| Codenamed | Alternative deception name is used by this unit on or after this date |
| Converted from | Unit is converted from another unit which had a different name or type to the new unit |
| Converted to | Unit is converted to another unit with a different name or type |
| Created | Unit is created or raised from scratch |
| Destroyed | Unit ceases to exist as a result of enemy action |
| Disbanded | Unit ceases to exist as a separate unit even on paper |
| Disembodied | Unit still exists but has no men |
| Dispersed | Unit is broken up temporarily |
| Divided From | Unit is created by the Division of other Units |
| Divided Into | Unit is divided into two new units with new identities |
| Embodied | Unit that was previously Inactive is staffed and equipped (equivalent to Mobilised) |
| Event | An event in the history of the unit |
| Inactivated | Unit still formally exists on paper but has no men or equipment and can be reformed in the future |
| Inactive | Unit is in existence and has men assigned to it but is not "mobilised" on a specific date |
| Location | Unit is in this location on a specific date (no longer used much) |
| Mobilised | Unit is mobilised or called up on this date |
| Other | Any other event in the history of the unit |
| Overrun | Unit was dispersed through enemy action |
| Reduced | Unit is reduced in size by reorganisation |
| Reduced to Cadre | Unit is reduced to a very small body of men but remains in existence |
| Reformed | Unit has previously existed and is recreated |
| Reinforced | Unit is increased in size as a result of reorganisation |
| Renamed | Unit is given a different title (used for minor changes to unit title) |
| Reorganised | Unit is restructured |
| Shattered | Unit is broken up into small fragments as a result of enemy action |
| Surrendered | Unit ceases to exist as a result of being forced to surrender |
| Suspended Animation | Unit still formally exists on paper but has no men or equipment and can be reformed in the future |