1. A method of photolithographically exposing a wafer using a target photomask within a target tool comprising: identifying first empirical alignment data that has been determined from use of the target photomask within at least one non-target tool; identifying second empirical alignment data that has been determined from use of a non-target photomask within the target tool; identifying third empirical alignment data that has been determined from use of the non-target photomask within the at least one non-target tool; calculating from the first, second, and third empirical alignment data predicted alignment data for the target photomask in the target tool; aligning the target photomask within the target tool using the predicted alignment data; exposing a pattern from the target photomask onto the wafer in the target tool; and further processing the exposed wafer.