Before solving, the goals must be converted to an IK/FK state that is used by the solver to output a skeleton state. Converting the goals to an IK/FK state is straightforward. The IK state uses both the rotation and translation, and the FK state uses only the extracted rotation. The FK and IK effectors that do not have corresponding goals (because no markers were assigned to the corresponding bones) get the values from the default stance pose.
You can adjust reaches to reach the IK goals or keep the FK ones. When reaching the IK translation, rotations that are up in the hierarchy might change to reach the translation. For this reason, the IK effectors have the same rotation as the FK effectors and if the rotation is kept, you can reach this rotation. For example, if the translation is set to reach the wrist IK effector, solving can change the extracted rotation on the elbow so that the wrist reaches the right position. If the elbow rotation (its angle) is important, set the reach on the elbow rotation so that it is maintained during the solve (which might result in the shoulder getting pulled).