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# Module 4: How a Passport Works in Practice

> The fourth module of the free tieback Academy DPP Foundations path: the scan path from carrier to record, identifiers versus resolvers, why a passport must persist after the sale, and why a published record should not change silently.

## Overview

Modules 1 to 3 established what a passport is and who has to produce one. This module answers a
different question: what actually happens, mechanically, once a passport exists. Most programmes
that stall after launch do so because nobody working on them can describe the scan path in enough
detail to diagnose a fault, or because the team quietly treats publication as the end of the job
rather than the start of a multi-year obligation. This module prevents both failures by walking the
path from carrier to record, separating the two components that get confused most often, and setting
out why a passport keeps working long after the point of sale.

**Estimated completion time: 40 minutes.** Four lessons of 8 minutes each, plus a ten question
assessment of about 8 minutes.

## Learning Objectives

#### Module learning objectives

Every objective is tested. Each assessment question is tagged to one of the four.

## Lesson Sequence

Then take the [module assessment](/docs/academy/foundations/module-4/assessment).

## Canonical Reading

This module teaches from three canonical articles. Each is the authoritative text and remains free
and open to everyone:

* [How Does a Digital Product Passport Work?](/docs/knowledge-base/digital-product-passports/how-does-a-digital-product-passport-work)
* [What is a Data Carrier?](/docs/knowledge-base/standards-and-technology/what-is-a-data-carrier)
* [What is a Product Identifier?](/docs/knowledge-base/standards-and-technology/what-is-a-product-identifier)

The lessons add sequence, framing, examples and practice. They do not restate the regulatory
content, and they never introduce a date, article number or citation that is not in the source
article.

## Frameworks Used

**TBF-004, The Digital Product Passport Data Flow.** Describes the stages a passport passes through
end to end, from product creation through to end of life, and places the scan path inside the market
access stage.

**TBF-009, The Product Compliance Transformation Model.** Describes the shift from document based,
point in time compliance to continuous, data based product accountability, which is why a passport
behaves less like a certificate and more like a record kept true over time.

Full descriptions of both are in the [framework registry](/docs/knowledge-base/frameworks/overview).

## The Running Case Product

Every Foundations module uses one product so the examples accumulate rather than reset.

**The Aurelia S2 cordless hedge trimmer.** A mid-price consumer power tool with a removable
lithium-ion battery pack, a moulded polymer housing, and a woven textile shoulder strap. This module
follows it through a failed scan, a tangle of internal identifiers, a battery replacement three years
after sale, and a correction to a mistaken published figure.

## Completion

The module is complete when all four lessons are marked complete and the assessment is passed at
the Foundations pass mark of 80 percent. Retakes are unlimited and your best score is kept.
Progress is saved on this device.

## Next Step

After the assessment, [Module 5](/docs/academy/foundations/module-5) moves from mechanics to timing:
when the obligation actually becomes mandatory, and why so much of the practical detail is still
missing.

## Related Docs

* [Lesson 1: The Scan Path End to End](/docs/academy/foundations/module-4/lesson-1)
* [Module 4 assessment](/docs/academy/foundations/module-4/assessment)
* [Module 5](/docs/academy/foundations/module-5)
* [DPP Foundations](/docs/academy/foundations)
* [How Does a Digital Product Passport Work?](/docs/knowledge-base/digital-product-passports/how-does-a-digital-product-passport-work)