[R] lm type of sums of squares

[Jarrett Byrnes]

I'm curious, I realize there are methods for Type II and III sums of 
squares, and yet, when I've been constructing models with lm, I've 
noticed that position of the term of the model has not mattered in 
terms of its p-value.  Does lm use sequential Type I sums of squares, 
or something else?

Thanks!

-Jarrett