Custom spiking is the addition of differing molar concentration of bases at a
single position, this is different from degeneracy at a position based on codons.
Codon based degeneracy is usually equimolar concentration of each base at the
same position (done at no extra charge for all internal and 5’ position, see
order form for single letter IUB codes). Custom spiking (example, 10% A, 75% G,
5% C & 10% T) has to be specified as required on the order form.
Custom column has to be prepared when the degeneracy and custom spiking is at
the 3’ position.