- Standard anchors are recommended for use on machine-readable forms (i.e. black squares, corners, crosses). The recommended number of anchors is five: four anchors in each corner of the form (they should form a rectangle if imaginary lines are drawn between each pair) and one square on one of the sides of the imaginary rectangle.
- If, for some reason, standard anchors cannot be used, we recommend that the following combinations of elements be used as anchors:
- at least two vertical line separators and two horizontal line separators
- at least four text elements and one form identifier element
- other combinations are also possible
- The distance between the edge of an anchor and the nearest form element should not be less than 3 mm.
- The distance between an anchor and the edge of the page should not be less than 8 mm.
- Anchors should be printed using a dark color (black is recommended) so that they do not disappear during scanning.
In addition to the general requirements listed above, each anchor type has its own specific requirements:
Requirements for Black Squares
Black squares on the same form type should all be of the same size i.e. between 4C…4 mm and 8C…8 mm. The recommended size is 5C…5 mm. Rectangles are not permitted.
Requirements for Crosses and Corners
- The size of an imaginary square that could be drawn around an anchor of this type must be between 4x4 and 8x8 mm. The recommended size is 5x5 mm.
- The size of anchors of one type must be the same within one form.
- All the sides of an anchor must be of equal size.
- The line thickness used for anchors on the same form must be the same and be within the range from 0.3 to 1 mm. The recommended thickness is 0.5 mm.
Requirements for Text (if used as anchors)
The font size should be at least 7 pt (and at least 14 pt for headers).
Requirements for Line Separators (if used as anchors)
Line thickness should not be less than 1 pt. The recommended thickness is 1-1.5 pt.
Requirements for Barcodes (if used as anchors)
- The barcode width (the distance between the leftmost and the rightmost bars) should not be less than 47-50 mm.
- The barcode height should not be less than 12-15 mm (digits not included).
- The barcode orientation (direction of the bars) should be the same as the page orientation (it is recommended to scan the pages in the direction of the bars).
- The EAN 13 barcode format is recommended.
- The minimum recommended distance between a barcode and any other form element is 10 mm.