This report presents the framework for replacing the current remaining service life (RSL) terminology with one based on more exact construction event terms. It provides detailed information on the research performed concerning remaining pavement life. It explores many issues that exist with the current RSL terminology that complicate proper interpretation, interagency data exchange, and use. While this report focuses on pavements, it is also applicable to other types of transportation infrastructure. A companion document provides step-by-step guidelines for implementing the RSI terminology. This report is intended for use by pavement managers and pavement investment decisionmakers across the United States.