Although companies and industries have developed their own interpretations, EDI transactions are largely based on two primary standards: ANSI X.12 and the more recent and global United Nations-sponsored EDIFACT. Developed at a time when network capacity was an important issue, the meaning of the data in an EDI document is positional; it's determined by where it falls in the message. In contrast, extensible markup language (XML) documents are self describing; they use actual labels, known as meta-data tags, to indicate whether a piece of information is a purchase order number or a UPC. Five years old this past February, the number of XML variations continues to grow, which can make it more difficult to use to exchange documents, especially across industries. That's one of the reasons it hasn't been adopted as quickly as predicted. Another is the fact that adding meta-tags to documents already being transferred by EDI only increases the number of characters, and consequently the network burden and cost of transmission. "Initially people thought that XML would eliminate some of the cumbersomeness of EDI. What really happened is people are looking at the benefits of both. Now they have multiple tools in their toolbox," explains Jeff Saunders, a managing consultant with EDS. Unlike the EDI standards, Saunders says the XML standards are only beginning to coalesce. "There are still a lot of folks who think their industry, their way of doing things, is unique so they propagate another set of standards, which is sort of an oxymoron."