AWS now supports the Zone Groups for Availability Zones across all AWS Regions, making it easier for you to differentiate groups of Local Zones and Availability Zones.
Zone Groups were initially launched to help you identify related groups of Local Zones that reside in the same geography. For example, the two interconnected Local Zones in Los Angeles (us-west-2-lax-1a and us-west-2-lax-1b) make up the us-west-2-lax-1 Zone Group. These Zone Groups are used for opting in to the AWS Local Zones.
You can now find the Zone Group for Availability Zones for all Regions in the DescribeAvailabilityZones API. For example, the Availability Zones in the US West (Oregon) Region make up the us-west-2-zg-1 Zone GroupName, where us-west-2 indicates the Region, and zg-1 indicates it is the group of AZs in the Region. This new identifier (such as us-west-2-zg-1) has replaced the previous naming (such as us-west-2).
For more details, please refer to the Zone Group for Availability Zones blog post and the visit DescribeAvailabilityZones API documentation.
Source:: Amazon AWS