The EM-COP Concept of Operations states a note should be left in the Whiteboard chat to let others know what you have updated or changed. This also means changes are time stamped.
If you have a Room open in an Incident you may see an asterisk on the Room tab. This denotes there has been changes or updates since you were last in the Room. In the example below, the Incident Map room has been updated while you have been in the Ground Observations room.