Wow, this is so interesting! Temporal maps are so interesting, and were an early research area at the University of Wisconsin at Madison, an early leader in computerized cartography. About the project talks about the history of the project. To put this in perspective, when they began in 1976 we were just beginning to apply computer technology to mapping in a few areas like the Census Bureau and the DoD. I was working in a computer cartography lab at that time.
I have just skimmed the full FDGC Metadata. It is also fascinating. Data quality includes attribute accuracy, completeness, positional accuracy and lineage with full source citations. I was surprised to see SDTS cited for the spatial data component (I contributed to developing this spec and thought it was deprecated).
