Already in the previous edition !
page 459, in Ternary Operator
This returns expr1 if boolean expression is true and expr2 otherwise.
-----> ^^^^^^^^^^^^^^^^^^
boolean expression should be boolean-expression (with hyphen) to correspond to the previous line
boolean-expression ? expr1 : expr2
as in if and unless Modifiers :
This evaluates expression only if boolean-expression is true (for if) or false (for unless).