Two brief advanced appearances are reported in this post in review of the Extreme section of Charles Timmerman’s Funster Hard to Extreme Sudoku.
In Extreme 60, the bypass starts with a 3-fill and uses them to solve a big wedge. The remaining line slink marking is easy.
The rest is easy too. A type 1 unique rectangle is enough for a collapse.
In funster Extreme 74, a less decisive bypass, . . .
. . . is aided by a 6-wing, a form of fish directly signaled by line marking. Regular fish of all sizes are now explained in the Guide as X-panel methods, but the X-wing is often spotted in line marking as an alignment of slink marks.
This fish has no victims now, but the fish icons are left in, to exclude 6 candidates from r46c3 and r4c7 in the remaining line marking.
As basic is completed, this XY-wing and naked pair triggers a collapse
Next in the review is Charles Timmerman’s funster Extreme 88. Next in the Guide is Coloring.