
· The following Table summarizes important fields in Tiger files.
Record Type  Field Name  Field Position  Description 
TLID  615  TIGER/Line ID  
RT 1  SIDE1  16  Single side? (blank = both sides, 1 = single side) 
FRLONG  191200  Start (from) longtitude  
FRLAT  201209  Start (from) latitude  
(Basic info  TOLONG  210219  End (to) longtitude 
for Lines)  TOLAT  220228  End (to) latitude 
TLID  1625  TIGER/Line ID (not all lines have an entry here  
RT 2  RTSQ  1618  Record Sequence Number (1, 2, etc) 
LONG1  1928  Start (from) longtitude of point 1  
LAT1  2937  Start (from) latitude of point 1  
(Detail points  LONG2  2837  Start (from) longtitude of point 2 
for Lines)  LAT2  etc  etc 
RT A  
(Basic info  POLYID  615  Polygon ID 
for Polygons)  
RT I  TLID  615  TIGER/Line ID 
(LinePolygon  POLYIDL  2736  Polygon ID on the left side 
info)  POLYIDR  4251  Polygon ID on the right side 
RT P  POLYID  1625  Polygon ID 
(More info  POLYLONG  2635  Internal Point Longtitude 
on Polygons)  POLYLAT  3644  Internal Point Latitude 
Pi = 3.141592;  
deg = (int)x;  
minute = x  deg;  
rad(x) = PI * (deg + 5.0 * minute / 3.0 ) /180.0; 
q1 = cos( rad(x)  rad(x') );  
q2 = cos( rad(y)  rad(y') );  
q3 = cos( rad(y) + rad(y') );  
D(p,p') = (int) (R * arccos[ 0.5*( (1.0 + q1)* q2  (1.0  q1)*q3 ) ] + 1.0); 
N.B. Assume points (q,f) on the equator projects to p(q,f)=(q, 0).