Rather than redirecting {{Country data Burma}} to {{Country data Myanmar}}, the former template transcludes the latter and passes through all parameters. The linked article will always be "Myanmar", but the displayed name is either "Burma" or "Myanmar" based on which of the two templates is used, even in templates that usually have a fixed default display name (such as {{flag country}} and {{fb}}). This allows for "Burma" to be used in historical contexts without having to also set |name=. The variants from {{Country data Myanmar}} can be used with both templates.
Examples
Redirects to Template:Country data Myanmar
Redirects to Template:Country data Burma
Myanmar
Myanmar