of this signature with classes 4 and 5 which are characteristic of medium den- 
sity urban areas (see before) occurs very frequently ; it can be detected in 
the periphery and sometimes but rarely inside the groupings made by both clas- 
ses. Such an association characterizes settlements located in the neighbour- 
hood of more densified urban or village cores. It points out the residential 
outgrowth of suburbs and outskirts. It is obvious that such an association also 
characterizes the periphery of the main city itself. 
An other class often goes cheek to jowl with class 6 and very fre- 
quently too with classes 4 and 5 : precisely the class 7. It indicates the 
existence of fallows and open land with mean reflectances, in the outward coun- 
try-side and in the external fringe of the new settlements outside of the town 
or villages. The association with class 8 is less systematic; it may occur 
in the absence of classes 4 and 5. In such a case, the class 7 indicates a 
transition between urban areas and light coloured fields, open building-yards 
or sport grounds (Fig. 1). 
The properly so called agricultural plots are depicted by four clas- 
ses on the listings : classes 10, 11 and 12 are characteristic; however, the 
class 10 may be associated with urban renewal sites (building sites); but, in 
this case, it is generally located on the periphery of classes values significant 
for multi-spectral higher reflectances (high reflecting sandy materials). Final- 
ly, class 9 characterizes humid meadows generally located cn the riversides (Pa- 
jottenland). See fig. 2. 
The association of classes used to define a specific form of land 
use is not always sufficient to make it clearly conspicuous. 
Thus, the family of reflectances (or their classes) defining the 
area shaped by the runways and parkings of the Zaventem airfield is similar to 
that one can find in renewal building-areas such as the new campus of the Uni- 
versity of Brussels in 1973 or the highway building-site of the "ring" around 
the capital. So the notion of geographically associated class must be completed 
by that of structural organization of the assembled values. In this case, 
the geometrical pattern of the signs on the listings due to the network of the 
runways is opposed to the lacking organization of the same values on the image 
showi 
a hij 
dent] 
makes 
appli 
assoc 
ciati 
urbar 
ponds 
than 
great 
cludi 
lower 
7, 8 
alway 
tance 
sing 
wide 
(fig. 
a var 
For e 
to th 
be me 
land 
urban 
other 
by th 
the h 
under 
It ob 
a phe 
agglo