《水经注·卷三十六》
区粟立了一根高达八尺的标竿，日影移到南边八寸，因为此影以南都在太阳的南边了，所以就以日南为郡名。
区粟建八尺表，日影度南八寸，自此影以南，在日之南，故以名郡。
Qusu erected a benchmark that was eight feet tall, and the sun moved eight inches to the south, because all this shadow was to the south of the sun, so it was named after the sun in the south. 