2. Direction
A direction is angle from a meridian to a line. It is similar to a horizontal angle in a traverse except the backsight is always along the meridian, Figure A3.
Figure A3 
There are two different ways to express line direction: bearing and azimuth.
a. Bearing
A bearing is an angle from the North or South end of the meridian turned to the East or West. A bearing has three parts:
 Prefix  N or S indicating which end of the meridian is turned from.
 Angle
 Suffix  E or W indicating turning direction from the meridian to the line.
N 66°40' E  from the North end of the meridian, turn 66°40' to the East.
Example
Bearing AB = N 66°40' E Bearing AC = S 55°32' E Bearing AD = S 44°21' W 

Figure A4 Bearings 
A bearing falls in one of four quadrants so the angle does not exceed 90°. The angle is to the right (clockwise) in the NE and SW quadrants, to the left (counterclockwise) in the SE and NW quadrants. A due North direction can be expressed as either N 00°00' E or N 00°00' W; due East as N 90°00' E or S 90°00' E; similarly for dues South and West.
A backbearing is reverse of a bearing, that is, Bearing BA is the backbearing of Bearing AB. Because the meridians are parallel at both ends of the line, the bearing angle is the same but quadrant is reverse. This is true only when meridians are parallel. Where meridians converge, the forward and back bearing angles will differ by the total convergence. More on this later.

Bearing AB = N 66°40' E

Figure A5 Back Bearing 
b. Azimuth
An azimuth is an angle to the right (clockwise) from the meridian to the line. In most cases the azimuth is turned from the north meridian end; earlier control surveys used the south end. An azimuth varies from 0° to 360°.
Example
Azimuth AB = 66°40' Azimuth AC = 124°28' Azimuth AD = 224°21' Azimuth AE = 322°26' 

Figure A6 Azimuths 
A backazimuth is reverse of a azimuth: Azimuth CA is the backazimuth of Azimuth AC. Because the meridians are parallel at both ends of the line, the backazimuth and forward azimuth differ by 180°. As with bearings, this is true only when meridians are parallel. Where meridians converge, the forward and back azimuths will differ by (180° ± total convergence). More on this later.
Example
Azimuth AC = 124°28' Azimuth CA = 124°28' + 180°00' = 304°28' 

Figure A7 