Internal IDÂ - a unique numeric identifier assigned internally by the eXpress software to uniquely identify each design element (object, port, function, test, etc.). It is because eXpress identifies the parts of the design using these Internal IDs that the software is able to easily distinguish between similar elements that have either been unnamed or have been assigned the same name (for situations in which the specific name assigned to an eXpress element has special meaning, refer to the discussion of Special Naming Considerations).