I believe the types are sin, cos, tan, and static. If you use static with scale, it just scales a static amount, for example scale static .5 static .5 would scale the texture coordinates down half way (making the texture appear twice as large).
Scroll is more or less the same way. If the type is static, it will just scroll in one direction at the specified speed. If you use something like sin, it will move back and forth in a wave-type pattern.