Example of a Buried Double
This is a screenshot
Two Squares in the same
that contain the same two
Possibles - and the Possibles occur nowhere else
in that same Row, Column, or Box.
In this example, the Buried Double is the two Squares containing the Possibles 1 and 4 (coloured cyan).
These two Squares MUST contain 1 or 4. Therefore they cannot contain any other Possibles. The 2, 5 (two occurances), 6 and 8
outlined in orange are impossible solutions and can be removed.