Defuzz nodes usually connect between rule nodes and output nodes. The defuzz value (set by the user) is used by the output node to determine the `crisp' output value (see fuzzy logic and output node).
The degree to which the defuzz value is being inferred is called the weight. This is displayed in the upper slider bar and number field (not user editable).
The defuzzification method is set in the output node.
In fuzzy logic theory this type of defuzz value would be called a singleton value. Normally defuzz values could also cover a range of real numbers, however this functionality is not currently available in Massive fuzzy logic.
Fuzzy else can be implemented by switching on the else button. The weight of an else defuzz node is automatically set to 1 - max, where max is the maximum weight of any other defuzz attached to the same output node. This is handy for default values (eg. hand position at side). Fuzzy else provides a way of under-specifying rules whilst maintaining stability although it is not generally recommended in orthodox fuzzy logic theory.
An incoming alt (black) input into the defuzz node sets the defuzz value to the value of the input, overriding the one specified by the user. The weight is still set by the normal incoming input.