.Modelica.Blocks.Sources.BooleanExpression .Modelica.Blocks.Sources.BooleanExpressionThe (time varying) Boolean output signal of this block can be defined in its parameter menu via variable y. The purpose is to support the easy definition of Boolean expressions in a block diagram. For example, in the y-menu the definition "time >= 1 and time <= 2" can be given in order to define that the output signal is true in the time interval 1 ≤ time ≤ 2 and otherwise it is false. Note, that "time" is a built-in variable that is always accessible and represents the "model time" and that variable y is both a variable and a connector.