This issue is related to recently submitted TISSUE #1761.
The description desc="Quad Box for connecting HSR ring to PRP network" is confusing. In IEC 62439-3(:2016) the term "QuadBox is only used to refer to a device coupling HSR rings, and that's how the term is known is the industry.
Solution will depend on what the outcome of TISSUE #1761 will be.
If TISSUE #1761 is accepted and the 4-port coupler is replaced with two standard 3-port couplers, then this whole ICD file element has to be replaced anyway
If TISSUE #1761 is rejected and the 4-port coupler is retained in the figure and ICD file, then replace the term "QuadBox" with "4-port coupler" or similar.
The term "Quadbox" is wrong, although a company could give it this name for a multi-functional device. To be corrected in the next edition.