NOAA maintains a government-wide index of environmental data. Created in 1989, it is being migrated to the FGDC format. For future generations to use data and analyses we are generating today, they must know where it came from-how it was measured, how it was processed, what it was intended to represent, limitation of instruments, conditions of observation, etc. More precision is not possible except for particular circumstances and uses. Human users want to search, browse, retrieve, ingest, process.
Computers require prescribed vocabularies, formats, and protocols.
There should be two or more to allow the market to influence future evolution to accommodate new technology, new methods. The use of object methods with inheritance, persistence, etc will help. Metadata is a conceptually deep problem that will never be solved completely. Data modeling is an essential part of the solution. Progress will come as many motivated groups tackle the identification and organization of metadata appropriate to their domains of interest.