oh man I'm having flashbacks to one of my first jobs after school. I spent a year writing a parser for that abomination of a format. Before I left I'd build a front-end and processing queue that did X12 -> XML and several modules to output the same data in various formats and flavors to suit the taste of various insurance companies... Parsing X12 was definitely among the least enjoyable things I've ever had to do. At the time I did it for way too little pay.