Naked Pair. (row 2,
left). A naked pair is made of two truths (blue) in two cells in row 2.
They are covered by two row links (red) in the same row. All digit 3s and
7s in row 2 are eliminated.
Hidden Pair. (column 8,
right). A hidden pair is made of two truths in column 8 for digits 4 and 9
(green). They are covered by two cell links (light blue). All digits in the
two cells are eliminated.
X-Wing. (r69 c36). An
X-Wing is made of two truths for the digit 8 in rows 6 and 9 (red). They
are covered by two column links (light green) in columns 3 and 6. All digit
8s in columns 3 and 6 are eliminated.