This entry and its opposite serve two different bodies of material in the atlas, and the join between them is a decision of the atlas rather than a claim made by either tradition.
The first is the Greek alternation of the signs described above. The second is Chinese. Yin and yang are a fundamental pair in Chinese cosmology, and they run through the Yijing, where the broken and unbroken lines of the trigrams and hexagrams are the yin and yang lines, through the ten heavenly stems, which alternate between the two, through medicine, and through the sexagenary calendar. The atlas holds all of that material under its own entries, and several of those tables carry a polarity value that resolves to this one.
Treating one table as serving both is efficient and it is a risk. The Greek property is a mechanical alternation of twelve signs derived from the elements. The Chinese pair is a general principle of complementary opposition applied across an entire cosmology, and it is not derived from anything more basic. They are not the same kind of thing, and a reader should not conclude from a shared label that a Greek feminine sign and a yin heavenly stem are two instances of one category.
So the atlas records the shared label, records that it is a modern convenience, and describes each tradition in its own terms elsewhere. Where a correspondence between the two has actually been proposed by somebody, it belongs under that proposal with its source attached, and not in the structure of a lookup table.
Sources TetrabiblosClaudius Ptolemy with A History of Western AstrologyNicholas Campion