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file1.art

% Having executed #set x = "10", the processor propagates value of x to all files reached along #adapt links.
% The first executed #set x overrides any subsequently found #set x commands in adapted files.
% An exception from the above rule is the situation where two #set commands assign values to the same variable
% in the same file. (on the same level)
Let's try the same with adapt-samlevel:
#set x = "10"
#adapt-samelevel "file2.art"
#set x = "20"
#adapt-samelevel "file2.art"

file2.art

% We adapted file2.art which creates a new scope level. The lower scope level cannot override variables
% defined on higher scopr levels, therefor the #set commands in this file won't override variables
% which are set earlier. This gives us the capability to have 'control' files on higher level
#set x = "AAA"
Value of x is ?@x?
% value now is "AAA".

file3.art

% ART is a configuration language not programming language. In some cases it has  to work differently than
% the programming languages we are used to. This is to better accommodate control over variations of the system
% we are generating

output

Let's try the same with dapt-samlevel:
Value of x is AAA
Value of x is AAA