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.