Amazon CloudWatch RUM (Real User Monitoring) adds the ability for customers to include additional customer-defined metadata attributes as key-value pairs to RUM events when instrumenting their web applications. Additionally, customers are now able to use these self defined attributes as an additional filter when slicing and dicing the data in the AWS Management Console. When combined with pre-defined metadata attributes (eg. browser, device, country) that RUM supports today, customers can see a better classification of different end user activities.
Source:: Amazon AWS