The codons, 64 in number, are distributed over the coding parts of DNA sequ
ences. The distribution function is the plot of frequency versus rank of th
e codons. These distributions are characterized by parameters that are almo
st universal, i.e., gene independent. There is but a small part that depend
s on the gene. We present the theory to calculate the universal (gene-indep
endent) part. The part that is gene-specific, however, has undetermined ove
rlaps and fluctuations.