What is with the green or white “laser” part trails in Assembly Instructions?

They don’t have any special meaning. I’m using GeoMagic Design to design the machine and drawing the illustrations. I like that software very much, but there are some shortcomings. One of them is that the part trail color is not user-selectable. Some cases the default white works fine, some cases it doesn’t. When it doesn’t, I draw green trails manually.

Btw, the illustrations are screenshots, where I have manually added the balloons. The screenshot utility I’m using is called Greenshot; highly recommended! The green part trails and number balloons are drawn in Greenshot as well.

(I have no association with either of the companies, just a satisfied customer.)