On the Subject of Boolean Venn Diagrams

Why is there a big Venn diagram? Why are there some weird symbols? Oh no...

See the original manual for the original instructions.

A     B     C A     B     C
X Y
AND
X Y
OR
X Y
XOR
X Y
IMPLIES
X | Y
NAND
X Y
NOR
X ↔' Y
XNOR
X Y
IMPLIED BY