All pointers that could be deterministically generated from existing values. I could store a pointer in a 64-bit field, or I could go mad with power, break it

All pointers that could be deterministically generated from existing values. I could store a pointer in a 64-bit field, or I could go mad with power, break it up into 11-bit chunks, and store it in the unused exponent of half a dozen float64 values, to be recombined later on. It's not to say that this would be a reasonable thing to do, but that these sort of shenanigans may be done (e.g. to pass data across an excessively narrow API callback)