-4.1 5 setxrange
-2 5.1 setyrange

/A {2 1} def
/B {-1 3} def

/U {2 4} def
/u {2 -3} def
/V {-1 2} def
/v {-2 1} def

quadrillage

[A B] points

20 setfontsize
setTimesItalic
   (A) A urtext
   (B) B urtext


[U V] points
U dupp u addv (->) line
V dupp v addv (->) line