Global regulators utilize the terms “primary,” “secondary,” and “tertiary” to distinguish between common packaging levels and to dictate which packaging level must bear a unique identifier for purposes of verification and/or tracing. However, this terminology is not aligned with the standard units of trade across the pharmaceutical industry. A lack of consistent terminology within and across markets has led to significant confusion. It is important that industry has clarity on packaging levels terminology and how best to utilize the various terminology. This document provides clarity on packaging level terminology and recommendations around how best to identify on which packaging levels/units a serial number should be applied.