Lesson 1: Anatomy of a CAP Alert Message

Aside from the codified elements, there are elements for entering information as text or as date and time values. The OASIS document describes the appropriate information to enter in these elements. Important ones are highlighted here:

Headline <headline>

A brief human-readable headline.  Note that some displays (for example, short messaging service devices) may only present this headline; it should be made as direct and actionable as possible while remaining short. 160 characters may be a useful target limit for headline length.

Description <description>

An extended human readable description of the hazard or event that occasioned this message. This is where you describe the important information (who, what, when, and where) about the hazardous situation.

Instructions <instruction>

An extended human readable instruction to targeted recipients.  This is where you place the important information (how and why) of your protective behavior instruction.

Area Description <areaDesc>

A text description of the affected area for human readers. Be as specific as possible. There are several elements related to Area Description that can be populated through mapping programs and can be machine interpreted (polygon, circle, geocode). Some warning systems use this information to provide a highlighted map of the area of concern or to send text messages to people within the area of concern.