> ## 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.

# Enum sheet reference

> Complete reference for defining and referencing enumerations in the NEAT physical data model Excel sheet.

An enum (enumeration) is a string field with a predefined set of values. Define enumerations in the `enum` sheet of the NEAT physical data model, then reference them in the `Value Type` column of the Properties sheet.

## Defining an enumeration

Add one row per value in the `enum` sheet. The following table shows `CogniteTimeseries.type` and `CogniteAnnotation.status` enumerations from the CogniteCore model.

| Collection               | Value     | Name      | Description                                         |
| ------------------------ | --------- | --------- | --------------------------------------------------- |
| CogniteTimeseries.type   | numeric   | numeric   | Time series with double floating point data points. |
| CogniteTimeseries.type   | string    | string    | Time series with string data points.                |
| CogniteAnnotation.status | Approved  | Approved  |                                                     |
| CogniteAnnotation.status | Rejected  | Rejected  |                                                     |
| CogniteAnnotation.status | Suggested | Suggested |                                                     |

The `Collection` column is the unique identifier for the enumeration. The `Value` column lists the allowed values. The `Name` and `Description` columns are optional and provide the display name and description for each value.

## Referencing an enumeration

Reference an enumeration in the `Value Type` column of the Properties sheet using the syntax `enum(collection=)`. Add an optional `unknownValue` parameter for unknown values.

| View              | View property | Value type                                | Container         | Container property |
| ----------------- | ------------- | ----------------------------------------- | ----------------- | ------------------ |
| CogniteTimeseries | type          | enum(collection=CogniteTimeseries.type)   | CogniteTimeseries | type               |
| CogniteAnnotation | status        | enum(collection=CogniteAnnotation.status) | CogniteAnnotation | status             |

## Further reading

* [Physical data model reference](/cdf/deploy/neat/data_modeling/excel/physical/reference) — Overview of all physical data model sheets
* [Properties sheet](/cdf/deploy/neat/data_modeling/excel/physical/properties) — Property definitions and syntax