1. I was not intending to writing raw XML. I was intending to write another program to write the XML files based on a map of waypoints and data. In a pinch, you could edit the raw XML files. Also, the authoring program could simulate the expressions that would be run through the scripting engine, with user-set variables and such to determine the expected result and error state.
2. If you had an autonomous editor, you could punch in coordinates of each waypoint and it would generate the XML file, and you could then go to each waypoint and set the states of mechanisms, scripts to be evaluated for values, check the results of the scripts given simulated data, check for errors, etc.
3. On error, you could revert to a alt. value, so the line that determined speed could look like this:
Code:
<speed script=1 alt=12>= 14 - ( (35 - nav_d__remain) * elev_error * .1 )</speed>