On a Sinar P, the tilt and swing axes coincide with the dashed lines on the groundglass, so you can tilt on the rear standard to find the optimal tilt angle, read the angle off the scale, apply the tilt to the front standard if you wish and reset the rear standard to vertical. The advantage is that you can see what is happening to the plane of focus on the groundglass without having to refocus.
On a Sinar F, you have a tilt/swing calculator that is best understood by reading the Sinar manual, which I believe was linked in another thread just yesterday, or you can check the Swiss Sinar website, where they have a description with good illustrations as I recall. The basic idea is that you set the needle on the calculator on the rear standard to zero, use the front standard to focus on the bottom dashed line, use the rear fine focus to focus on the top dashed line, and then read the tilt angle off the calculator. Use the same procedure with the left and right dashed lines for swing.