Structured Andunstructured Data In Operational Support Tools Have Long Been Prevalent Insoftware Engineering. Similar Data Is Now Becoming Widely Available In Otherdomains. Software Systems Thatutilize Such Operational Data (Od) to Help With Software Design and Maintenanceactivities Are Increasingly Being Built Despite the Difficulties of Drawingvalid Conclusions from Disparate and Low-Quality Data and the Continuingevolution of Operational Support Tools.