Each of the 12 Placidus house cusps falls at a specific degree in the zodiac, governed by a sign lord, star lord, and sub-lord.
KP principle: The cuspal sub-lord is the ultimate lord of that house signification. If you ask "Will I marry?" (7th house question), the cuspal sub-lord of the 7th house cusp is the deciding factor—not the 7th house lord (classical lord) or the star lord at that cusp.
Example: 7th house cusp at 14°22' Pisces. Classical lord is Jupiter. Star lord (nakshatra lord) is, say, Saturn. Sub-lord is Venus. In KP, Venus is the lord of marriage for this native, not Jupiter.
The 249 sub-lord map: All 360° of the zodiac are divided into 249 successive sub-lord arcs, creating a detailed map. Each arc is governed by one of the 9 Vimshottari planets, cycling repeatedly. No degree is without a sub-lord.
Application: To answer a horary question, the astrologer identifies the cuspal sub-lord of the relevant house and checks whether it is benefic (promising the outcome) or malefic (denying it). The sub-lord's conjunction with planets, its strength, its nakshatra lord, and its aspects all refine the verdict.
The calculator identifies cuspal sub-lords for all 12 houses in a chart. You will examine your own chart's cuspal sub-lords and correlate them with your life events (marriage, children, career) to test whether KP's principle holds.
Promise is the gate. The cuspal sub-lord answers one question: are the matters of this house available to this person at all. If the answer is no, KP holds that nothing downstream can deliver them. No dasha, however favourable, and no transit, however exact, can produce an event the chart does not promise. This is the discipline that separates KP from timing-led astrology.
How the verdict is reached. Find the sub-lord of the cusp in question, then establish which houses it signifies through its star lord, its occupancy and its lordships. If it signifies the houses supporting the matter, the promise stands. If it signifies the houses that negate it, the matter is denied.
The 7th-house example. For marriage, the 7th cuspal sub-lord should signify houses 2, 7 or 11: family expansion, partnership and gain. If instead it signifies 1, 6 and 10, the classical KP reading is denial of marriage, because those houses describe separateness and self-sufficiency rather than union.
Practising restraint. A denial verdict is a serious statement about someone's life, and it rests on an accurate birth time and correct significator analysis. Where the birth time is uncertain, report that the method cannot give a safe answer rather than delivering a denial you cannot stand behind.