Dealing with two-layer DRs on real wafers is much more difficult. For example, edge-to-edge overlay5 (EE OL) in two layers’ patterns’ separation and extension (also known by application-specific terms “poly-to-active endcap,” “contact-to-metal enclosure,” “contact-to-metal space,” etc.) involves critical dimensions in both patterns and their centerline layer-to-layer overlay. Capability of direct in-line EE OL metrology still does not exist—another gap in DR validation. Although EE OL may be estimated using in-line measurements of two layers’ CDs and OL, in IC manufacturing practice,6 the required CDs and OL are not measured on the same tools or on the same patterns, and their respective control loops are separate. However, two-layer DRs being yield-limiting parameters and OL their largest component, EE OL recently got much attention, with EPE declared as the overlay-related lithography technology showstopper… What does EPE, the foundation of model-based OPC, have to do with overlay? Nothing: this EPE is not that EPE. Although the recent appearance of the term EPE in the industry’s dialog on EE OL may appear as a sign of discovery, no new control parameter was identified. It is still the old one, just a new name. The new language denies the very existence of two-layer DRs and ignores the long-present gaps in DR validation and control. Not only is the new language not helpful in closing the technology gaps, the resulting confusion disrupts the industry dialog on the real issues. Be that as it may, confusing language is not an obstacle for you to comprehend Part 2: Image Placement, Device Overlay, and Critical Dimension. Our authors made an effort to “speak standard SEMI” and to use standard JM3 acronyms whenever possible, and to define or at least illustrate exactly what they mean by the terms which others may find confusing. In one case, you are given the motivation for a new definition, terminology, and performance metric in a new application. Authors rigorously define the subject, explain why those changes are needed, and even trace their new definition to the long-existing SEMI standard. Would you, JM3 reader, expect anything less?