Used as an UDA to mark a variable of a type that looks like GC-managed but that is actually not GC-managed, because its allocated by malloc, calloc or some other non-GC allocator.
When this enum is used as UDA on aggregate types whose instances are created with construct() a compile time message indicates if a GC range will be added for the members.
Indicates if an aggregate contains members that might be collected by the garbage collector. This is used in constructors to determine if the content of a manually allocated aggregate must be declared to the GC.