A repository contains multiple versions of an Azure Pipelines template, and you will deploy multiple pipelines that use a stored template. To guarantee each pipeline uses a fixed template version, which reference should you use?

Using a branch reference (e.g., template@releases) ensures that all pipelines using this reference will consistently pull the template from the specified branch. This provides stability, as the template version remains fixed to the state of that branch. While SHA-based hashes (template@sha:abcdef123...) also guarantee a fixed version, they are less practical for ongoing development and maintenance. Each time the template changes, the SHA in every dependent pipeline would need updating, leading to significant overhead. Branches allow for controlled updates: once a template is stable on a releases branch, for example, all pipelines referencing it get that stable version. Serial numbers are not a standard method for versioning templates in Azure Pipelines. Runners refer to the agents that execute pipelines, not a method for referencing template versions.