I should add here that I always worked with hewn material that continued to carry the chalk line lining marks on all the finished framing surfaces.
I expect that most of you work with smoothly finished surfaces, and possibly no lining chalk marks.
During the fitting process the frame's long segments are laid out in the fitting area, on top of six by sixes and held tightly in position using timber dogs, while all the other segments are tapped into their positions.
Then using measuring poles of varying lengths the measurements are double checked using the intersecting points of the chalk lines to ensure their accuracy and also to ensure that they will properly meld into the finished frame as a whole.
I hope that I have explained how these sets of timber dogs would be used in the fitting process