A dynamic expression for an output port of a primitive data type runs the expression against each port to generate multiple output ports. A dynamic expression for a dynamic complex output port runs the expression to construct a dynamic complex port and returns a single output port of a complex data type.
You must specify a base port for the dynamic expression. Base port setting determines how the elements of the output complex port must look like. For example, elements of a port selector determine the elements of a dynamic output array. Base port for a struct determines the types of the elements of the output struct port.
When you configure a dynamic expression, the Developer tool does not validate whether you have specified a base port.