+ * <pre>
+ * Aligned nucleotide positions for codons mapped to column positions of of aligned
+ * proteins. e.g.
+ * codons[3] = [12, 14, 15] means:
+ * column 4 in the protein alignment translates cols 13, 15, 16 in cDNA
+ * codons[5] = null means column 6 in the protein alignment is a gap
+ * </pre>