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Mapping and charting conventions from five national and international authorities read side by side. The group exists because a symbol that means one thing on an Ordnance Survey sheet can mean another on a USGS quadrangle, and because the IALA buoyage system reverses its lateral colours between Europe and the Americas — the one difference in this domain that will put a vessel aground. Several members carry a warning rather than a definition: an underlined number on a chart is a height and not a depth, a contour interval changes what identical line spacing means, and a map legend is authoritative for its own sheet alone.
The stated height difference between adjacent contour lines.
A thickened contour line carrying its height figure.
A contour with inward ticks, marking ground that falls.
A dot with a number giving an exact elevation.
A line with hatching or a rock-face texture on the falling side.
Short horizontal tufts marking waterlogged ground.
Regularly spaced tree dots marking cultivated planting.
A hatched or textured area marking extraction.
A long-dashed line marking a right of way for horses.
A dashed line marking a right of way for vehicles.
A ruled line of a rectangular coordinate system.
Three arrows showing grid, true and magnetic north.
A thin circle marking a control point's centre.
Hatched or cross-hatched area a competitor may not enter.
Graded green shading showing how slow the vegetation is.
An underlined number showing ground exposed at low water.
A channel-side buoy whose colour depends on the region.
A buoy whose two cones say which side holds safe water.
A black and red buoy with two black balls.
A red and white striped buoy with a single red ball.
A yellow buoy with a yellow cross topmark.
An abbreviation giving a light's rhythm, colour and period.
A hull or crossed-mast mark showing a sunken vessel.
An anchor mark showing where a vessel may anchor.
Broad arrows and a bounded zone dividing shipping lanes.
Small letters saying what the bottom is made of.
A shaded relief rendering of rock faces on Alpine maps.
Names and codes identifying a topographic sheet and its neighbours.
French national mapping's distinct symbol and colour choices.
A printed ratio saying how much the map reduces the ground.
The printed key explaining a map's symbols.