ActionScript 2.0 :: Converts 3d Coordinates To 2d Coordinates - Difference Between MoveTo And LineTo?

I was reading the 'Isometric Transformations' tutorial by Danko Kozar and I have a few questions. I understand what all the code does, but not how it does it. First of all, how does the following code work:

transforms x,y,z coordinates into Flash x coordinate
xFla = function (x, y, z) {
// cartesian coordinates[code].....

I understand that it converts 3d coordinates to 2d coordinates, but I don't understand how. What numbers whould be punched into x, y, and z to acquire certain desired effects?Also, what's the difference between moveTo and lineTo:

red line
style(1, "0xFF0000", 100);
plot(0, 0, 0);
draw(200, 0, 0);