> For the complete documentation index, see [llms.txt](https://docs.yarnspinner.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.yarnspinner.dev/3.1/api/csharp/yarn/yarn.header/yarn.header.keyfieldnumber.md).

# KeyFieldNumber

Field in [Header](/3.1/api/csharp/yarn/yarn.header.md)

## Summary

Field number for the "key" field.

```csharp
public const int KeyFieldNumber = 1;
```