public String toString() {
        return "sorting '" + (isAscending() ? '+' : '-') + function.toString() + "(" + strength.toString() + ", " + locale + ")";
    }
A search-time document attribute sort specification(per-document in-memory value).
This belongs to the attribute or field(implicitt attribute).

@author baldersheim
config-model/src/main/java/com/yahoo/schema/document/Sorting.java