The Slot property defines the location of a submodule within the module.
Slots must be always in ascending order.
When no Slot property is defined, the index within the containing module defines the ordering of submodules.
When one submodule in a module defines a Slot property, all submodules of the module must have a Slot property.
Slot property must be used if the user wants to replace a default 'autocreated' submodule of a module on a specific Slot with a submodule of other type.
When no Slot property is defined, and an 'autocreated' submodule of other type is found on that Slot in the module, compile will break and the user has to decide how to solve it:
If the user wants to replace this 'autocreated' submodule, the user has to specify explicitly the Slot property for it,
or if the user wants to only parametrize this 'autocreated' submodule, the user has to specify the matching TypeIdentifier of the 'autocreated' submodule.