extent, but they are also liable to structural changes. Through a number of recent
legend improvements, the rural character of the Dutch topographic map has already
been subdued. Research is still being conducted to look into the possibilities of
expansion of the legends for the urban areas.
Such legend adaptions are not only required to eliminate the detrimental effects of
the legends on the landscape representations, but also often to eliminate the
anachronisms in the legends. Standard legends work more or less like a filter which
withdraws certain topographic data from the map image. Like gases or vapours which,
according to Kirchhoffs Law, withdraw light of certain wavelengths from poly-
chromatic light which passes through such gases, so do national Standard legends
withdraw certain monothematic elements from the polythematic-topographic land
scape ranges on maps when applied to specific landscapes or townscapes. The
topographic maps resulting from such 'absorbing legends'present an incomplete picture
I.
Topographical Map 1 25 000. Belgium sheet 31 3/4 Brüssel (fig. 3 nr 11) with a wide topographic
ränge for built-up areas, orography and roads. (Published with the consent of the Militair Geogra-
fisch Instituut, Abdij ter Kameren 13, 1050 Brüssel).
K.N.A.G. Geografisch Tijdschrift VI (1972) Nr. 3
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