In computer science's object-oriented programming, class variables (static fields) contain information which is associated with all instances of a class. If all tanks have one cannon, then it is not necessary to specify, in an instance variable for each tank object, that each tank has only one cannon; rather, one can simply define a class variable which does this and thus all instances of the class will share the variable.
... Atkinson and Margaret,
mother of Henry VII., who did the fourth book.
Translations appeared in Italian (Venice, 1488,
Milan 1489), Spanish (Seville, 1536), Arabic ...