If I understand this correctly the King is the only piece that can be captured by displacement. All other pieces can only be captured by jumping over them, and there is no limitation to the number of pieces you can capture this way. (Well, the limitation is put by the board size.) Only the final square has to be empty or contain a King. Knights are supposed to move along an L-shaped path, (long leg first), and are the only pieces that can jump over friendly pieces.

In principle the Interactive Diagram should be able to do this: In XBetza notation the sliders are just multiple mcaf steps, up to 6 times, followed by a final leg with mk mode. For the Knight there first are exactly two mpca steps before it turns sideways for the mk final leg, as it can also hop over obstacles.

For some reason the Diagram doesn't correctly perform these discriptions, though. I suppose there is a problem combining destructive (c and non-destructive (mp) modes on the same leg. For the Knight I could fix that at the cost of far higher complexity of the XBetza description (mpcafmpcasmkW should have been enough). This seems to be a Diagram bug that should be fixed.

[Edit] Oh, stupid of me. Because the sliders cannot jump friendly pieces, a much simpler description is possible. E.g. (caf)6mkB instead of (mcaf)6mkF. Because B is a slider the intermediate m steps are automatically bridged, and no combination of m and c modes is necessary. Apart from capture during castling everything now appears to work.

BTW, this is a nice demonstration of the Diagram's new move-entry system, with up to 7 pieces captured in one turn!