All or nothing is one of the possible generalizations of the biconditional

It means AND OR NOR:

   ${\displaystyle ~\lor ~}$          ${\displaystyle ~\Leftrightarrow ~}$       

Apart from the line with no arguments it is the same as AND XOR NOR:

   ${\displaystyle ~\oplus ~}$          ${\displaystyle ~\Leftrightarrow ~}$       

Image set Variadic Boolean functions (16×16 tables)
AND	OR
XAND	XOR