minutes in a degree; and never more than 60 seconds in a minute.     1.  Latitude lines are called Parallels of Latitude.     Latitude originates at the equator at 0°.  It increases toward the north and south poles to 90°.  It is labeled N or + for positions in the northern hemisphere; S or - for positions in the southern hemisphere (i.e. 34°N, +34°, 34°S, -34°).  See Figure 2-16.   Figure 2-16    Parallels of Latitude 2.  Longitude lines are called Meridians of Longitude. Longitude originates with 0° at the Greenwich Meridian for most geographic systems; however, some systems reference other meridians as the 0° origin or Prime Meridian (see paragraph 2-21).  It increases east and west toward the International Dateline at 180°.  In the eastern hemisphere, longitude is labeled E or +; in the western hemisphere, it is labeled W or - (i.e. 107°E, +107°, 107°W, -107°).   In some cases, the position of a point may include a longitude in excess of 180° E.  These are converted to the standard format by subtracting the longitude from 360° (e.g. 206°E = 154°W).  The north and south poles do not have a longitude.  See Figure 2-17. E W + 90° 90° 60° 60° 30° 30° Figure 2-17    Meridians of Longitude     3.  A network of lines on a map representing parallels of latitude and meridians of longitude is called a graticule.  See Figure 2-18.  A graticule can represent the entire globe or a small region of the earth. Figure 2-18    Graticule c.  Convergence.  The inclination of two meridians toward each other is called Convergence of the Meridians or more commonly Convergence.  All meridians of longitude are parallel at the equator and intersect at the poles.  See Figure 2-18.  The conver- gence of the meridians at the equator is 0°.  At the poles, the convergence is equal to the difference between the longitude values of the meridians. Between the equator and the poles the convergence varies from 0° to the difference in the longitude values. Because of this, a geodetic azimuth and its back azimuth will differ by the convergence.     2-19  Geodetic Coordinates a.  Geodetic Coordinates are the quantities of latitude (   ), longitude (   ), and ellipsoid height (h) which f l define the position of a point on the earth's surface with respect to the reference ellipsoid.  This type of geographic coordinates are the most commonly used by surveyors and cartographers.  If the reference ellipsoid is geocentric (i.e.. WGS-84), the coordinates are termed Geocentric Geodetic Coordinates. b.  The geodetic longitude of a point on the earth's surface is the angle formed by the intersection of the plane containing the Prime Meridian (x-z cartesian plane) and the meridional plane containing the point. The geodetic latitude  of a point is the angle formed by the intersection of the equatorial plane (x-y cartesian plane) and a line which passes through the point and is perpendicular to the reference ellipsoid. DRAFT 2-9