---
title: Shielding VCL Rendering, New VCL Syntax
summary: null
url: https://www.fastly.com/documentation/reference/changes/2024/03/vcl-changes
---

Backend definitions with [shielding](https://www.fastly.com/documentation/guides/concepts/shielding/) enabled, and which use the 'shield' director, now have a simplified syntax that incorporates health checks, loop checks, and other checks in a single line of VCL.

Additionally, the minimum version of VCL available across our network increased, unlocking the following changes:

## New variable

- `tls.client.ja4`

## New function

- `time.interval_elapsed_ratio`