Lesson 1: Anatomy of a CAP Alert Message

Here is another example of the previous message processed for display on a web page showing all the element values:

How the message is displayed or processed will depend on the warning system and the target audience. Through the use of server applications, certain elements of the message can be used to trigger dissemination and processing of the message. Depending on the type of alert, it may be sent via email or text, it might be a pop-up on a web page, it may get processed by a machine reading application on a radio or TV station, or it might take some other form. For instance, an application can be programmed to trigger a siren if certain values are present in a message:

Note that those three elements — urgency, severity, certainty — are key elements used to emphasize the importance of an alert. Their values indicate when to take protective action, what impacts the event will have on life and property, and how certain it is that the event will happen.