This document discusses the challenges of managing complexity in software and systems development. It proposes two approaches to address this complexity: 1) variant management through strategic reuse, defining entry points and reuse strategies; and 2) product line engineering, shifting from asset reuse to sharing across a product line lifecycle. IBM's solutions involve its Rational tools integrated with BigLever's product line engineering framework to support requirements, modeling, quality management, and an overall lifecycle approach. The combination aims to improve productivity, quality, and time to market through feature-based development and automated production.