At the beginning we have different product data models for batteries, laptops, textiles and so on. They describe the required structure and data fields. Let's take the following simplified product data model of a laptop:

• Technical Specs (Section)
  • CPU (Numeric Field, model level)
  • Memory (Numeric Field, model level)
• Sustainability (Section)
  • Carbon Footprint (Numeric Field, item level)
  • Carbon Footprint calculation method (Text Field, model level)

A product data model is built up of sections where each section consists of a list of data fields.

The product data model describes the structure and data fields of a passport. However, the data values of all the data fields are stored either in a model or item passport. But what is the difference between a model and an item? Actually, these are different levels of granularity. Let us take the laptop example again. The model can be something like an Apple MacBook Pro 2019 | 16. Now let's say Bob has such a laptop and Alice too. These laptops are individual items of the model Apple MacBook Pro 2019 | 16. They have different serial numbers. For simplicity, let's call the laptop of Bob item 1 and the laptop of Alice item 2. Both items have some values like the memory or CPU in common. All the values which are the same over all items are stored in the corresponding model passport Apple MacBook Pro 2019 | 16. However, item 1 and item 2 can have different carbon footprints since they are manufactured in different factories, such that the transportation causes other carbon footprint values. Therefore, the carbon footprint values are stored in the individual item passports.

Let us bring everything together. The product data model describes the structure and data fields. It also defines the granularity level of each data field. Having the product data model we can create a model passport from it. A model passport defines the values of the data fields which are the same over all items. At the end, having a model passport we can create item passports from it. A item passport references all the data values on the model level. Additionally, it defines the values of the data fields which can be different to other items.