Represent iso-norm-definitions in entities

Question

I got an entity MyEntity with a field MyField. This field only accepts the following values: S11, S12, S219 and S231.

To realise this, I used an enum:

@Entity
public class MyEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column
    @Enumerated(EnumType.STRING)
    private MyEnum myEnum;

    // ...

}

public enum MyEnum{

    S11("description of 11"), //
    S12("description of 12"), //
    S219("description of 219"), //
    S231("description of 231");

    private String description;

    private MyEnum(String description) {
        this.description = description;
    }

}

Now I got a countryLocation which should be conform with ISO 3166-1 alpha-2. Is there any nice way to solve this problem? At the moment I just mapped this like:

@Entity
public class MyEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column
    @Size(min = 2, max = 2)
    private String countryLocation;

    // ...

}