I am tinkering with tables opened with fopen() and I'm also looking at them with a hex editor. I have observed that for any field numbered n:

OFFSETn = (FIELD LENGTH n -1 + FIELD LENGTH n - 2 + ... + FIELD LENGTH 1) + 1

i.e. the sum of all previous field lengths + 1.

Q: Is this always true, or is it possible for a field's offset value to be independent of the order of its description in the table header?

Thanks.