In codon usage studies, it is observed that a correlation between ENC and GC3 values is plotted as a curve following Wright's, 1990 method and hypothesis. However, what should be the case when a genome is AU rich and thereby contains AU3 content higher than GC3? Does higher abundance of AU3 holds any significance in comparison to GC3? In this case, should there be a plot between ENC and AU3 rather GC3?