Look into following one of the Ruud 50K Specialty puzzle:

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`4.97...3.1....24....7.......91..5...6...3...5...6..84.......7....32....6.5...93.8`

After a hidden single, a box-line reduction intersection removal and a pointing and claiming intersection removal moves (by my solver and one hidden single and two pointing and claiming intersection removal moves by SudokuWiki Sudoku Solver), got (same) following state:

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`+---------------+---------------------+-------------------+`

| 4 268 9 | 7 1568 168 | 1256 3 12 |

| 1 368 568 | 3589 5689 2 | 4 56789 79 |

| 2358 2368 7 | 134589 145689 13468 | 12569 15689 129 |

+---------------+---------------------+-------------------+

| 2378 9 1 | 48 2478 5 | 26 67 237 |

| 6 2478 248 | 189 3 178 | 129 179 5 |

| 2357 237 25 | 6 1279 17 | 8 4 12379 |

+---------------+---------------------+-------------------+

| 289 1268 268 | 1358 1568 1368 | 7 1259 4 |

| 789 1478 3 | 2 14578 1478 | 159 159 6 |

| 27 5 246 | 14 1467 9 | 3 12 8 |

+---------------+---------------------+-------------------+

Checked next move on Andrew Stuart's SudokuWiki Sudoku Solver that suggest as follows:

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`WXYZ Wing`

The four cells {D4,E6,J4,F6} contain in total 1/4/7/8.

Candidate 1 determines the 'wing' cells (in yellow) and one or other of those 1s must be true. Therefore...

1 can be taken off E4

1 can be taken off G6

1 can be taken off H6

My first question is that, is WXYZ-Wings (or BarnS=4) Apex cell contain only two clues?

Whereas, my solver suggest next move as follows:

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`Found WXYZ-Wings Type 3 Cells 68 75 41 50 Clues 1478 remove Clue 1 from Cells 59 77`

After that, next move might contain an XY-Wings Transport (either ERI or Line) Ring move.

R. Jamil