MicrosoftDocs/azure-docs#38893

Author: mimckitt

articles/container-registry/container-registry-tutorial-quick-task.md

@@ -74,7 +74,7 @@ The commands in this tutorial series are formatted for the Bash shell. If you pr
 
 Now that you've pulled the source code down to your machine, follow these steps to create a container registry and build the container image with ACR Tasks.
 
-To make executing the sample commands easier, the tutorials in this series use shell environment variables. Execute the following command to set the `ACR_NAME` variable. Replace **\<registry-name\>** with a unique name for your new container registry. The registry name must be unique within Azure, and contain 5-50 alphanumeric characters. The other resources you create in the tutorial are based on this name, so you should need to modify only this first variable.
+To make executing the sample commands easier, the tutorials in this series use shell environment variables. Execute the following command to set the `ACR_NAME` variable. Replace **\<registry-name\>** with a unique name for your new container registry. The registry name must be unique within Azure, contain only lower case letters, and contain 5-50 alphanumeric characters. The other resources you create in the tutorial are based on this name, so you should need to modify only this first variable.
 
 ```azurecli-interactive
 ACR_NAME=<registry-name>