A run of cells resolved by singles once a key cell is placed
A unit with one empty cell takes the only missing value
A cell with a single remaining candidate must take it
A value that fits in only one cell of a unit goes there
A letter/digit pair already used elsewhere cannot be reused
A letter/digit pair that fits in only one cell goes there
A cell whose only valid letter/digit pair is left is forced
A pair confined to one row or column cannot pair with other symbols there
Two pairs of one symbol confined to two cells lock those cells
Three pairs of one symbol confined to three cells lock those cells
Four pairs of one symbol confined to four cells; other pairs of that symbol are blocked at those cells
A 2x2 restricted to two letters and two digits has no valid completion (no order-2 Graeco-Latin square)
A pair placement that no line matching, symbol transversal or coupled cover admits is impossible
Two cells holding the same two candidates lock them in the unit
Three cells whose candidates union to three values lock them in the unit
Two values confined to two cells lock those cells
Three values confined to three cells lock those cells
Two rows locking a value to the same two columns clear those columns
Three rows locking a value to three columns clear those columns
A bivalue pivot and two bivalue pincers eliminate their shared candidate
A trivalue pivot with two bivalue pincers eliminates the shared candidate
Two bivalue cells linked by a strong link eliminate the other candidate
Conjugate links followed in two colors; a contradiction removes one color
A chain of bivalue cells whose ends share a candidate clears it from common peers