Provided is a polybenzoxazole precursor having a high purity which does not contain ionic by-products. The fuel injection system has a high-pressure pump, from which fuel flows to a first rail and a second rail which each have respective associated injectors for the two rows of cylinders. The advertising and marketing materials are displayed on the recipients’ devices as images on the display, as backgrounds to caller IDs, as sidelines to picture messages, as headersfooters to a text messages, etc. A second cyclic extension symbol inserter inserts a cyclic extension symbol into the u-th user signal.