> For the complete documentation index, see [llms.txt](https://infosys.selmotech.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://infosys.selmotech.com/selmo-solution/selmo-solution-en/selmo-documentation/8-diagnosis-hmi-and-documentation/documentation-from-the-model.md).

# Documentation from the model

### Evidence & Audit

This chapter describes, **how documentation is created in Selmo**\
and why it **does not have to be created or maintained manually**.

Documentation in Selmo is:

* no additional effort
* not a separate document
* not a subsequent result

But:

> **A structured view of the formal model.**

***

### The fundamental problem of classic documentation

In classic automation projects, documentation is often:

* temporally downstream
* decoupled from the code
* incomplete or out of date
* hard to trace

Typical situations:

* the code works, the docs are outdated
* changes are not applied consistently
* behavior cannot be conclusively proven
* audit questions must be interpreted

The problem is **not a lack of diligence**,\
but the lack of a **common source of truth**.

***

### The model as the single source

In Selmo the model is that source.

The model already contains:

* process (sequences, states)
* Structure (plant, hardware zones, zones)
* behavior (Bit-Control)
* Monitoring (interlocks, CMZ, checks)
* reactions (stop, release, diagnosis)

That provides everything that is necessary for documentation.

> **What is described in the model,**\
> **can be documented.**\
> **What is not modeled,**\
> **cannot be documented.**

***

### Which documentation is generated from the model

From the model the following can be automatically derived:

* Process descriptions\
  → states, transitions, sequences
* Structure overviews\
  → plant, hardware zones, sequences, zones
* Safety arguments\
  → interlocks, CMZ, plausibility checks
* Diagnostic descriptions\
  → zones, expectations, deviations
* Operating concepts\
  → manual and automatic operation, HMI semantics

This documentation is:

* consistent
* up-to-date
* unambiguously
* fully traceable

***

### Traceability and audit

Through the formal model it is always traceable:

* which state is active
* which conditions apply
* which monitoring applies
* why a reaction occurs

For audits this means:

* no interpretation of code
* no assumptions about behavior
* no detached descriptions

Instead:

> **An explicit, verifiable behavior model.**

***

### Documentation and changes

Changes are made in Selmo:

* to the model
* not to individual documents

This means:

* every change is central
* all derivations remain consistent
* no diverging document versions

> **Change in the model =**\
> **change in code, diagnostics and documentation.**

***

### Distinction from classic documents

To clarify:

* Documentation ≠ PDF
* Documentation ≠ textual description
* Documentation ≠ collection of comments

Documentation is:

> **a formal representation of the model**\
> **from different perspectives.**

***

### Benefits of model-based documentation

Through model-based documentation the following becomes:

* engineering more transparent
* operation safer
* commissioning more efficient
* auditing easier
* responsibility provable

> **Documentation becomes from a mandatory document**\
> **an integral part of the system.**

***

### Summary

Documentation in Selmo:

* is generated automatically from the model
* is always up to date
* is clearly traceable
* supports evidence and audit

> **Whoever understands the model,**\
> **also understands the documentation.**


---

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