Extra POI Editor

GPX allows you to set both speed and distance alert triggers. Proximity is the distance, set the preference under options so the top dropdown shows imperial and the other two remain metric. Putting a value in speed will set a speed trigger. These work the same as running POI Loader in manual except with POI Loader you only get to set one.

You can set a field to a single value using the CTL-R key combination, the short cut to Replace Field.

My understanding of alerts in "TourGuide" files is that they operate within a "radius" of x feet from where the GPS is (ie. any direction). Other alerts work at the "distance" ahead on the street on which the GPS is proceeding. This means that, if the POI is on a sidestreet to the street on which the GPS is proceeding, there will be no alert (even if you can see the POI as you pass it by).

After reading this a number of times and downloading a bunch of times I think I understand.
The alert distances are now showing up on the page in the gps as well. Never noticed that before.