Curly braces {...} surround a function or a procedure call. The function And has two arguments and returns a value. The procedure Browse has a single argument and no return value.   

However, every function is actually a procedure as well - with one argument more. For example, And is actually a procedure with three arguments. This is shown by the second example, where And binds the variable B. 

Please note the order of computations in this example. Firstly, B is browsed. Afterwards, And binds B to false. However, Browse does indeed show the correct value of B. This is possible, because Oz variables are logical variables, which can be used to communicate information between different parts of a program.