Planner Template (.plat) Files

You found that publishing a Basic plan creates a .plat file in the Team’s SharePoint library and want to know whether it can be moved, cataloged, or edited manually. The supported reuse boundary is Planner’s custom-template experience, not direct file manipulation. A published template is associated with the Microsoft 365 group selected during publishing, and access follows group membership. Members reuse it from Shared or Created by me. For another group, publish the source plan as a template to that group. If the source changes, update the plan and publish a new template version; existing plans are unaffected. Microsoft’s guidance lists the plan elements selectable during publishing, but it does not document the .plat schema, a supported editor, or a move-and-register workflow. Do not build a production catalog by relocating or editing those files. Use dedicated groups for broader audiences and treat the SharePoint artifact as Planner-managed data.