A method of processing a data stream comprising: (a) receiving said data stream including a watermark message encoded within said data stream; (b) extracting a corresponding recovery file location from said watermark message; (c) receiving a recovery file based upon said recovery file location that includes a corresponding content identifier; (d) selectively extracting said content identifier from said recovery file when said content identifier is an object that includes properties of a pattern expression to express a constraint as a string, where said string is entertainment identifier register information.