If you were spelling 'boat,' for instance, you would begin with an E, the third letter after B; then R for the O, being the third letter from O.

So you'd spell 'boat,' ERDW; and Senora Estrada knows when she gets that despatch that she must count three letters BACK from each letter to get the right ones.

Take now such a cipher word as ULIOH.

That means RIFLE.

Count three letters back from each letter of ULIOH, and it'll spell RIFLE.