The highly customized ERP (enterprise resource planning) systems in place at companies around the world are looking a bit long in the tooth, to the point where by 2016 it will be common practice to refer to them as "legacy" software, according to analyst firm Gartner. These systems are showing their age in a number of ways, chief among them their monolithic, all-in-one structure, Gartner analysts Denise Ganly, Andy Kyte, Nigel Rayner and Carol Hardcastle wrote in a report announced Wednesday.