WGS 84 Comments on CAP

[bschroeder@esri.com]

Most of the world uses meters, however the aeronautical navigation people use feet. So if most of the CAP messages where height is needed are related to flight warnings or restrictions then it should be feet. 
 
Most of the US States use feet - however some use the international survey foot vs the US foot. Some of them have agreed that when they provide data to USGS it will be in meters. So it's all screwed up. 
 
I think we should pick one - and demand all messages use it. Probably ft.
 
I think we let people provide what ever level of precision they want.
 
If the polygon in the message covers an area that can be drawn on a 1:250,000 scale map - only single precision is needed. 
If the message is trying to precisely describe several city blocks then you need double-precision
 
We would need to know exactly how it's to be used before we could say one or the other.
 
In a majority of cases double precision is overkill and causes the coordinate strings to be voluminous.