The ALLDIFF statement can have multiple specifications. Each specification defines a unique global constraint on a set of variables, requiring all of them to be different from each other. A global constraint is equivalent to a conjunction of elementary constraints.

For example, the statements

var (X1-X3) A B;
alldiff (X1-X3) (A B);

are equivalent to

If the variable list is empty, the ALLDIFF constraint applies to all the variables declared in any VARIABLE statement.