> I'm going on the assumption that we can assume it's an opaque reference of equal size as a pointer to data that is or will be in the machine's user-mode memor

> I'm going on the assumption that we can assume it's an opaque reference of equal size as a pointer to data that is or will be in the machine's user-mode memory. If the handle is an array index or a hash, it can be much smaller than a pointer. 8 bits in extreme cases, often 16 bits (if there's only a few thousands objects of that type), and we almost never ever need more than 32 bits. Such handles can easily have less memory overhead than actual pointers, even after accounting for the redundancies needed for some runtime checks.