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We strongly recommend that the <area> entity defines the geographic area to be
notified, not the incident area.
In the case of a tropical storm, we recommend that the <area> entity contains
<polygon> or <geocode> elements that denote the places where you expect
impacts from strong winds, heavy rain, or other threats from the storm. If a
storm is still offshore, then don't set the <area> entity of your CAP alert
to the storm's current location.
Similarly, in the case of a forest fire, we recommend that the <area> entity
data also includes towns or places where you expect impacts from smoke or other
threats from the fire.
area entity sub-elements
Element name
Optionality
Type
CAP and Google notes and requirements
<areaDesc>
REQUIRED
string
To generate the location text string used in the alert title or
headline, Google might use an <areaDesc> element. Keep
the <areaDesc> value short (less than 50
characters).
<polygon>
OPTIONAL
string
The paired value points in a <polygon> element
define a polygon that delineates the area to alert in an alert message.
We recommend that you represent the <polygon> element
by a whitespace-delimited list of
WGS84
coordinate pairs.
Polygons must meet the following requirements:
They must be closed.
They can't overlap.
Holes (like in donut-shaped polygons) and intersections aren't
supported.
A minimum of four coordinate pairs are required. The first and last
pairs of coordinates must be the same.
<circle>
OPTIONAL
string
The <circle> element consists of paired
point-and-radius values that delineate the area to alert in the form of
an alert message. We recommend that you represent the
<circle> element by a central point: a WGS84
coordinate pair followed by a space character and a radius value in
kilometers.
Note: If you specify a circle with zero or a very small radius, Google
can't show the alert to our users.
<geocode>
OPTIONAL
string
Define the <geocode> element with values from a accessible
and open dataset of polygons. As an example, in the US, these values come
from the following data sources:
FIPS6
UGC code
SAME
US Zip Code
If you use geocodes, provide Google with a fixed list of
geocode-to-polygon and shapefile maps. To post notices of updates to this
list, use a separate channel, preferably as RSS or email alerts. For
example, US NOAA publicly publishes their
geocode updates.
<altitude>
OPTIONAL
float
The value of the <altitude> element is the specific
or minimum altitude of the affected area of the alert message. Provide
this measurement in feet above mean sea level according to WGS84
datum.
<ceiling>
CONDITIONAL
float
Use the <ceiling> element only if the
<alert> entity contains an
<altitude> element. The value of the
<ceiling> element is the maximum altitude of the
affected area of the alert message. Provide this measurement in feet
above mean sea level according to WGS84 datum.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-05-07 UTC."],[[["The `\u003carea\u003e` entity in a CAP alert should define the geographic area expected to be impacted by the event, not the event's location itself."],["When defining the alert area, use `\u003cpolygon\u003e`, `\u003ccircle\u003e`, or `\u003cgeocode\u003e` elements to specify the impacted locations."],["For alerts covering multiple, non-continuous areas, create separate `\u003calert\u003e` messages for each distinct area."],["Ensure the alert area remains within your organization's jurisdiction to avoid publishing issues with Google."],["Each `\u003carea\u003e` block must include at least one `\u003cpolygon\u003e`, `\u003ccircle\u003e`, or `\u003cgeocode\u003e` sub-element for accurate location specification."]]],["The `\u003carea\u003e` entity should define the impact zone, not the incident's location. For events like storms or fires, use `\u003cpolygon\u003e` or `\u003cgeocode\u003e` to specify areas affected by threats, not the storm's position. Use separate `\u003calert\u003e` messages for noncontinuous areas. All `\u003carea\u003e` blocks must include at least one of: `\u003cpolygon\u003e`, `\u003ccircle\u003e`, or `\u003cgeocode\u003e`. Ensure the areas are within your jurisdiction. Additional elements like `\u003careaDesc\u003e`, `\u003caltitude\u003e` and `\u003cceiling\u003e` are also defined.\n"]]
