I've been a software engineer since 1991, writing software for the Grocery industry. I've been writing C for 31 years, 7 years developing with Java/Tomcat/Maven, 9 years with C#, and 5 years with Android. I've got extensive experience interfacing with various point-of-sale systems (IBM 4680/4690/ACE, Toshiba ACE/SurePos, Retalix ISS-45, ECRS Catapult, NCR Emerald, Innovax, SASI, etc). Also have 29 years of experience with DEX. In my world, DEX is "direct exchange", which is an RS232 serial standard used to exchange invoice information between stores and vendors.