! (LogiX node)
The ! node performs the logical NOT operation on input A.
When spawned from the node browser, this node accepts an int datatype by default, but it is more commonly used to work with Boolean values (True/False) where it inverts whatever input it receives — True becomes False / False becomes True. This node will accept some numeric datatypes, in which case it performs the operation in a bitwise manner.
The most common use of the node as a boolean operator simply inverts the value it receives. True becomes False, and False becomes True.
In this case, the ! node is being used to invert the output of a Boolean Latch so that it can toggle two values at once, where one must be True while the other is False.