Lucky Panda 432 offers a clear example of a less encountered type of boxline, on the way to becoming a Sysudoku Basic casualty.

In line marking, the newly formed naked pair 13 removes 3r2c4, leaving two aligned 3’s in the North box. One of these must be N3, so the remainder of c6 can have no 3’s. Sysudoku labels this interaction of box and line a boxline.

A reversed form of boxline would occur if 3r8c6 were removed instead, leaving no 3’s in  c6 except the two in the N box. This would require the 3 of c6 to come from r12c6, removing 3r2c4.

The details are all there in the basic trace.

Next is the conclusion of the Lucky Panda review, with 480.