---
title: uuid.is_version5
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/uuid/uuid-is-version5
---

```
BOOL uuid.is_version5(STRING uuid)
```

**Available in:** all subroutines

Returns `true` if string holds a textual representation of a valid Version 5
UUID. Returns `false` otherwise.

## Example

```vcl
if (uuid.is_version5(req.http.X-Unique-Id)) {
  set beresp.http.X-Unique-Id-Valid-V5 = "yes";
}
```