The products in a Product Line Engineering (PLE) portfolio are described by the properties they have in common with each other and the variations that set them apart. The descriptions are in terms of the products' features. Products can comprise any combination of:
For example, the products can be software-only (such as a financial accounting system); software-embedded (such as an automobile, aircraft, cel phone, or a smart home appliance); or a manufactured item such as a piece of furniture.
When we refer to a product in PLE, we usually mean not only the primary entity being built and delivered, but also all of the assets that are produced along with it. Some of these support the engineering process (such as requirements, project plans, design modes, and test cases), while others are delivered alongside the thing being built (such as user manuals, shipping labels, and parts lists).