Major Jacob Westfall; While CAP was never meant to be a GIS substitute, most alert messages have a need to better describe the geo information related to an incident. To date the use of the area block to fulfill this role has been dubious. As the spec says, area segments are used to describe the geographic area for which the info segment applies. They are not used to describe elements of the incident like the incident site, evacuation route, etc and invalid workarounds like using circles with radius 0 to slip in a point value are cumbersome. I recommend extending the role of resources to include supplemental geographic information. Resources are already filling this role for other types of information and this will keep the area segment from being misused. Outlined below is an approach that could be considered, we have been using it through a namespace extension for over a year now with great results. In order to "geo enable" the resources block, the following simple geometry elements are added, point, line, polygon, and circle. All using WGS84 with lat, lon and spaces between point values in lines and polygons, and between the point and radius in circles. Also another element is added to resource blocks to allow for classification and automation, resourceType. This new element allows for data layers, also known as profiles, to define a common list of classifications for resources and the info they contain. The following MVA example illustrates the use of geo resources in an incident message:
<resource>
<resourceDesc> Motor Vehicle Accident Site </resourceDesc>
<resourceType>
<valueListUrn> http://www.example.com/resources </valueListUrn>
<value> incidentLocation </value>
</resourceType>
<point> 1,1 </point>
</resource>
<resource>
<resourceDesc> Detour Route </resourceDesc>
<resourceType>
<valueListUrn> http://www.example.com/resources </valueListUrn>
<value> trafficRoute </value>
</resourceType>
<line> 1,1 1,2 1,3 1,4 </line>
</resource>
Geo resources can also take advantage of other resource elements like uri, perhaps when referencing an incident site the uri links to an image or video feed of the incident, or for any important locations like an evacuation route or shelter site the reference also includes a WAV in spoken word for sight impaired users. The resources block becomes very useful when it can fulfill this role of providing useful supplemental geo-information, while the area block remains as intended.