> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cognite.com/llms.txt
> Use this file to discover all available pages before exploring further.

# About the physical data model

> Learn about the physical data model and how it implements your conceptual model in CDF Data Modeling Service (DMS).

The physical data model implements your conceptual data model in Cognite Data Fusion (CDF) via the Data Modeling Service (DMS).

Use `NeatSession` to read and write data models to Excel files:

```python theme={"languages":{"custom":["/_languages/kuiper.json","../_languages/kuiper.json"]}}
from cognite.neat import NeatSession, get_cognite_client

client = get_cognite_client(".env")
neat = NeatSession(client)

# Reading an existing data model
neat.physical_data_model.read.excel("path/to/excel/file.xlsx")

# Writing a data model to an Excel file
neat.physical_data_model.write.excel("path/to/excel/file.xlsx")
```

For a reference of the physical data model, see the [physical data model reference](/cdf/deploy/neat/data_modeling/excel/physical/reference). For detailed explanations of each component, see the [properties sheet](/cdf/deploy/neat/data_modeling/excel/physical/properties), [views sheet](/cdf/deploy/neat/data_modeling/excel/physical/views), [enum sheet](/cdf/deploy/neat/data_modeling/excel/physical/enum), and [units](/cdf/deploy/neat/data_modeling/excel/physical/units).