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`......3.1`

86.......

...2.....

....4.76.

..1......

.......8.

.7....64.

5..1.3...

...5.....

Like this puzzle is 17-clue but it only has 64 Hidden Single.

Hidden Single has 3 kinds

1. Only remaining empty cell of the block, row or column (1.0)

2. Only possible position of one value in block (1.2)

3. Only possible position of one value in row or column (1.5)

But Naked Single (2.3) is more difficuly then Hidden Single and one kind

1. One value is the only possible value for a cell

562149378

000678125

178253649

000800063

000405x07

000300900

006500030

210034806

400086000

On the R5C7 cell ( I bold x there ) is the only possible value of 2, because the mid-right block, row 5 and column 7 already have 1,3,4,5,6,7,8,9, this cell can only put 2 in.

Bacause there isn't a 16-clue puzzle of normal Sudoku, the maximum Hidden Single is 64. And all of puzzle are solved by Hidden Single when the last some steps. Naked Single should don't have as many as 60 you said, but I am sure there are puzzles needing more than 5 steps of Naked Single, I don't find yet.