We need to use a multiplexer in-line with a 40GBASE-KR4 interface that runs over a backplane. The DS125MB203 datasheet makes a reference to KR, but there is no explanation of what the settings do. Also, we have noth seen any information on how well it supports KR. We are concerned that the 203 will interfere with training and adjustments made between the two endpoints. Is there any additional information or support for multiplexing KR interface signals?