public CategoryURLGenerator getSeriesItemURLGenerator(int series) {

        // return the generator for ALL series, if there is one...
        if (this.itemURLGenerator != null) {
            return this.itemURLGenerator;
        }

        // otherwise look up the generator table
        CategoryURLGenerator generator
            = (CategoryURLGenerator) this.itemURLGeneratorList.get(series);
        if (generator == null) {
            generator = this.baseItemURLGenerator;
        }
        return generator;