RULES AND PRACTICES 11 



In general, disturbance notes (printed in magenta) shall be used where deviations of 2° 

 or more from the normal value of magnetic declination exist (except that in Alaska a lower 

 hmit of 3° shall be used). 



Examples 



LOCAL MAGNETIC DISTURBANCE 



Differences from normal variation of as much as 5" have been 

 observed in Gastineau Channel in the vicinity of Lat. 58° 15'. 



LOCAL MAGNETIC DISTURBANCE 

 Differences of 12" or more from normal variation may be 

 expected in X Channel in the vicinity of Z Point, 



When limited by space, the full note should be placed elsewhere on the chart and the 

 following reference note shown (in magenta) in the area of disturbance: 



LOCAL MAGNETIC DISTURBANCE 

 (See Note) 



STATE PLANE COORDINATES 



In areas where the Corps of Engineers and other agencies use State Plane Coordinate 

 systems as survey control, the coordinates shall be shown by dashed ticks in the borders of 

 New Charts and of charts being corrected. These ticks, at selected intervals, shaU consist 

 of three dashes, with a total length of 4.0 mm. and a line weight of .005 inches. Where a chart 

 is of sufficient east and west extent to indicate grid curvature, intermediate ticks shall be used ; 

 intermediate ticks should preferably be selected to fall on land, but where needed to control 

 major channels (or on special request by local users) such ticks may be charted in water areas. 

 In the latter case the chart notes shall include this symbol and its explanation. 



The border ticks shall be labelled to indicate clearly the interval used. The last three 

 digits of the grid value shall be omitted. The remaining significant digits shall be placed 

 parallel to the grid tick rather than to the neatline (See Fig. 4). By connecting the ticks 

 with straight lines they can be used for control of Corps of Engineers' surveys. 



When a State Plane Coordinate Grid is indicated, the following note format shall be placed 

 on the chart: 



PLANE COORDINATE GRID 

 Oregon State grid, north zone, is indicated 

 by dashed ticks at 5,000-foot intervals. 



Charts now showing dotted ticks for Plane Coordinates are to be changed to dashed ticks 

 and new labelling only when the chart is reconstructed. 



