Source counts exact em dash characters and word tokens using its regular expression. One hypothetical em dash among one thousand words normalizes to ten per ten thousand; two normalize to twenty. Bars share twenty-five pixels per dash per ten thousand words. Exact punctuation frequency alone does not identify an author or prove text was generated by a model. Keeping one exact em dash while doubling hypothetical token count from one thousand to two thousand halves normalized frequency from ten to five per ten thousand. Bars share forty pixels per unit. En dashes and intra-word hyphens are separate counters, so visually similar marks do not enter this numerator. For hypothetical rate ten and stored reference six, source subtracts six then divides six, giving about sixty-six point six seven percent above the reference. Bars compare the two rates at fifty pixels per unit. The stored benchmark labels and research attribution are not independently verified, and the heuristic density verdict is not reliable AI detection. Complete raw JSON and native reset/resize/footer checks preserve the existing analysis tool.