URDF frame

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Hello! I have some questions on the URDF frame. From the figure in this page (URDF Joint element), I find that the joint's elements <origin>, xyz and rpy are relative to the parent frame. Which frame does the parent frame here refer to? Does it refer to the previous joint frame?

Another question: From the figure in this page (URDF Link element), I find that the properties of the link's inertial <origin>, xyz and rpy are relative to the link reference frame. Could you please explain which frame does the link reference frame here refer to ? Does it refer to the joint frame in this figure (black)?

Any advice is appreciated.

Thanks!