The Y-chromosome DNA (Y-DNA) results chart headings are color coded in two ways. First, each testing level (Y-DNA1-12, Y-DNA13-25, Y-DNA26-37, Y-DNA38-67, and Y-DNA68-111) is coded with a different shade of blue. Second, the STR (short tandem repeat) markers that have faster mutation rates and are more likely to change within the genealogical time frame are coded with a red background.