1.1.1 Pin/Node Definition

Since the pin definitions must be declared at the beginning of the source file, their definition is a natural starting point for a design. Nodes and pin nodes, which are used to define buried registers, should also be declared at the beginning of the source file. Pin assignment needs to be done if the designer already knows the device to be used. However, when creating a VIRTUAL design, only the variable names that will later be assigned to pins need to be specified. The area that normally contains the pin numbers will be left blank.