Document Object Model

In technical terms, XML files are described through a “document object model” which details the  underlying structure and elements of a message. The details of this are more important to someone that needs to develop a program to author or process CAP messages than it is for someone that is issuing alerts. However, being familiar with the technical aspects of CAP will help assure that alert authors are providing appropriate information for their alerting system and target audience.

Here are the structure and elements, the document object model, of a CAP alert message:

CAP DOM

In descriptive terms, an alert message contains information about an event (or multiple events) which can contain multiple supporting resources and area descriptions. The elements that describe each of these are made up of XML tags containing values.