f3218016_Element_IDs__Id_Description
[Ids & Syntax] {gCalMarkup _id/}.mainTemplate.container[.groupId] [Template] Yes [Id Description] 
An optional container element that contains the above template element. A container element is required in cases where the template element is not valid HTML by itself. For example for a tabular calendar where the template is a element it must be inside a container element to be valid.
Element IDs
Id Description