Ken & netCDF Group... Thank's for the reply. I guess lately I've been reading too much Guy Kawasaki and my latest horiscope says... "...you're blessed with a disquieting talent for asking questions no one else has the nerve to. You wouldn't be afraid to don a giant chicken suit if it helped you prove a point." I think what has made me a bit off lately is confusing DIMENSIONS in a data/file definition sence, with POSITIONS in space and time -- ie., the theoretical v.s. the practical. What it comes down to for the average tech/PI with raw data is this -- "I want to make a graph of time vs temperature", "I want to plot the tracklines from the cruise", or "Where were we when we took water sample 38, and what was the flow-through temp and conductivity?" One thing I can see a good data file format must manage is this: every platform will have some position at a given time. This position may be fixed or variable, and probably defined by some high-precision device like GPS. This position will be global for the platform. Global in the sence you use it in programming. Many instruments will inherit this global position, or will derive a position by some offset from the global position. And to make it more complex, this offset may be variable, or it may be fixed. So, how do you manage global and local coordinates for data samples in a clean, simple form? To take a word from OOP, INHERITANCE is a good possibility. The big catch though, is making something that works. -Tim