One division of the Drekkana spans 10 degrees, three to a sign and thirty six in the zodiac. The ascendant crosses ten degrees in roughly forty minutes, which puts the D-3 among the tolerant charts: a birth time good to the quarter hour will usually place the rising drekkana correctly.
The counting rule is the most elegant in the scheme. The three divisions of any sign are assigned to that sign, to the fifth from it and to the ninth from it, which is to say to the three signs of its own trine. A planet in the first ten degrees of Aries falls in the Aries drekkana, in the second in Leo, in the third in Sagittarius, and the same pattern of self, fifth and ninth repeats from every sign. Because a trine shares an element, the drekkana of any planet is always in the element of the sign it occupies.
The Drekkana belongs to all four classical groupings. More than one drekkana scheme is in circulation, and the assignments above are the Parashari one that the shodashavarga presumes; where a text or a program uses another, the chart it produces is a different object and should be labelled as such rather than compared directly.
Its subject is the sibling, and beyond that the courage and initiative the tradition reads as belonging to the same part of life.