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revision 05/00
Magnetic north lines are lines placed on the map lines pointing to magnetic north. Their spacing on the map should be 33.33 mm which represents 500m on the ground at the scale of 1:15000. For maps with other scales lines placing should be at intervals which represent a round number of metres (e.g. 50 m, 100 m, 250 m, 500 m) and the spacing should be between 20mm and 40mm on the map. North lines may be broken where they obscure small features such as boulders, knolls, cliffs, stream junctions, path ends, etc. In areas with very few water features, blue lines may be used.
The sides of the map (paper) should be parallel to the magnetic north lines. Dimensions: black line width 0.14mm (blue line width 0.18mm). Colour: black (blue)
The North Line symbol is defined in the IOF Specification as follows:-
"North lines are black 0.125 - 0.175 mm lines pointing to magnetic north.
Their spacing on the map should be 33.33 mm which represents 500m on the ground at the scale of 1:15000. North lines may be broken if they obscure small features such as boulders, knolls, cliffs, stream junctions, path ends, etc.
In exceptional cases blue 0.175 lines may be used.
The sides of the map (paper) should be parallel to the magnetic north lines.
Arrowheads may be used to show magnetic lines."
For 1:10000 maps the spacing of grid lines should be 25mm which represents 250m on the ground.
ISOM number introduced.
No symbol is provided in the default symbol set.
For 0.114mm black lines a new symbol will have to be defined, the lake bank line symbol (301.1) is no longer appropriate..
To use a 0.18mm blue line a new symbol will have to be defined.
We do not recommend a thinner line than 0.18mm.
Use the straight line tool for drawing. When drawing, it is easy to see if the line is true by checking for a jump from one vertical line of pixels to the next (aliasing)
Zoom in and check the location of the end point (the preferences will need to be set to allow the co-ordinates display). The co-ordinates are the two figures displayed in the centre of the bottom strip of the screen. The first number of the co-ordinates is the easting, this should be exactly the same for the upper and the lower point of the line. Adjust the points to get a true vertical. Use this line to make true vertical copies.
Competitors with poor eyesight (or sweat in their eyes) do not appreciate 0.125mm lines on 1:10000 maps especially in feature rich terrain.
Note that blue north lines may be used, especially when there is very little blue line detail. Consult with your map adviser.
Drawing North Lines
Make the north lines longer than are needed,
stretching well above the map boundary,
so that they can be moved together by selecting them
all at their ends without grabbing any other object.
They can then be all moved about the map and checked
against the template north lines for direction and spacing.
Once the map is complete they can be shortened to the required length.
Shorten the north lines by cutting at the right point and deleting the excess, not by moving the end point.
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