You can choose a set of templates saved in your sandbox space by using an appropriate sandbox prefix. For example, if you want to preview a version of ଛାଞ୍ଚ:Test that you have saved as "ବ୍ୟବହାରକାରୀ:Foo/sandbox/ଛାଞ୍ଚ:Test", use "ବ୍ୟବହାରକାରୀ:Foo/sandbox" as the prefix.
