This is a lengthy post,  explaining our VNAV situation, or at the least, how we arrived where we are today, and where we're going from here.  This is a tale of how being too ambitious and trying to be all things to all people bit us and our customers.  In the beginning was nav data in XML format....whether other formats were avail in the beginning, I don't know, I only know this was my beginning because I inherited the FMS work and this was the dataset that landed on my plate.   It was from