Astrologically, the point defined by the western intersection of the prime vertical and the ecliptic, opposite the anti-vertex in the east. Generally, it is the point on a limb of an object farthest from an observer's horizon. The Moon's vertex is used in observations of lunar occultations. The longitude of the Vertex may be computed with the formula: ARCCOT (-((COT f x SIN e) - (SIN RAMC x COS e))/COS RAMC), where e is the obliquity of the ecliptic and f is the angle between the zenith and the RAMC. For the mid latitudes, the position of the vertex with an astrological chart is predictable, occurring one or two houses either side of the Descendant angle. Time of day, time of year, and exact latitude are variables in the position of the Vertex. For subtropical latitudes the position of the Vertex is very erratic, just as the position of the Ascendant is in extreme northern or extreme southern latitudes. For a birth at 0 latitude, the Vertex and the Descendant would be one and the same, as would the Antivertex and the Ascendant. In other words, the Vertex and Equatorial Ascendant axes are one and the same for births at 0 latitude. Jayne observes that the Vertex is the descendant of the horizonal house system. Today, the vertex is generally thought of as a sensitive "relationship point"; an astrologer would look for contacts between the vertex and transits or progressions, or planets in another's chart. For example, one person's vertex in conjunction with another's person's Venus: this establishes a love connection. The vertex has even been noted in horary charts, allying the querent with the quesited person (the ascendant in a horary chart is frequently used in this way). Jayne and Johndro are credited with simultaneously and independently giving the vertex interpretive prominence in astrology. Johndro called the Vertex the "electric ascendant" and Jayne thought of the vertex as the whole Vertex/Antivertex axis, and wrote of its "significant end . . . on the setting side of the chart." Using traditional astrological interpretation of the eastern half of the horoscope as "personal" and the western half as "impersonal" (the split occurring along the Midheaven axis), Jayne called the vertex "the most fated of the three Angles" (the others being the ascendant and midheaven): The vertex is naturally of interest in assessing relocated natal charts, since as the "third angle" of the chart it is sensitive to change. For example, relocation moves Venus from the fifth house to the sixth house, and moves the vertex to a partile conjunction with Venus (where there is a separation of several degrees in the natal chart); relocation, then, involves a sort of double emphasis on relationships, bringing Venus, which relates to love, together with the vertex, a sensitive point in relationships. In this sixth house, this relocated suggests a "nonseparation" of work and love with a very critical element; aspects to this formation would determine the nature and productivity of the criticism.