The keyword expression uses the following syntax. Operators are executed strictly from left to right. Expressions inside parentheses are always executed first.

expression
	element [operator element [operator element [...]]]
element
	keyword	True if keyword exists in the list
	"keyword"	True if keyword exists in the list
	*	True if keyword list is not empty
	(expression)	True if expression is true
	!element	True if element is false
operator
	&	AND: True if both elements are true
	|	OR: True if either element is true (or both elements are true)