You can also request a tag sort, where the file byte offeset addresses
of the sorted records are left in the output file (for cases where you
don't have twice the original data size available).

Of course it can't deal with arbitary fields beyond the expected
strings, integers, reals and T/F, nor does it sort variable length
records (but could easily changed to do so, nor does it cater for non-
MS byte order and FP formatting), but I see no need for the formal
route suggested.