Two block instances are said to be wired together if one block's input feed is attached to the other's output feed. Output fields from the source block's output feed then need to be mapped (that is, connected) to the destination block's input feed's input fields.

The Block Wiring tab displays a solid blue labeled rectangle for each of the block instances that have been added to the scenario. Unless re-organized, these will initially be displayed in a partially overlapping stack at the top-left of the tab.

If a block instance has one or more input feeds, its rectangle will have a wiring point on the left hand side. This is a small solid black semi-circle. Similarly, if it has one or more output feeds, its rectangle will have a wiring point on the right hand side. Blocks with both input and output feeds exhibit wiring points on both sides. The figure below shows the Block Wiring tab.