-2.5 2.5 setxrange
-1 1.5 setyrange
100 setheight

/A {-2 0} def
/B {2 0} def

%% syntaxe : A B manip
/manip {
   4 copy               %% A B A B
   4 copy               %% A B A B A B 
   2 3 div hompoint     %% A B A B A'
   3 1 rollp            %% A B A' A B 
   1 3 div hompoint     %% A B A' A"
   4 copy               %% A B A' A" A' A"
   -60 rotatepoint      %% A B A' A" A'"
   2 -1 rollp           %% A B A' A'" A" 
   4 -1 rollp           %% A A' A'" A" B
} def

[A B manip]
dup points
dup ligne
dup {2 marked} 2 4 Apply

setTimesItalic
   (A) A ultext 
   (B) B urtext