> Dear all, I'm also glad to see this discussion surface. Since I first presented "Developing Conventions for netCDF-4" at the 2007 GO-ESSP meeting:
http://www.unidata.ucar.edu/presentations/Rew/nc4-conventions.pdf I've been hoping that netCDF-4 feature adoption would begin to gain traction in the community (see slides 19 and 20 of this 2010 presentation for my "chicken-and-egg logjam" illustration): http://www.unidata.ucar.edu/presentations/Rew/agu_2010_nc4_Rew.pdf I like the Zender-Habermann-Leonard (ZHL?) proposal for Group Attributes, but would like to point out a potential problem for its use with HDF Groups: they aren't actually hierarchical. In HDF5, Group A can be a parent of Group B, which in turn can be a parent of Group A, forming a cycle instead of a hierarchy. The graph of the Group-subGroup relation in HDF5 can form an arbitrary directed cyclic graph, though this is not permitted in netCDF-4, in which only Group *hierarchies* can be created through the netCDF-4 API. Without a restriction to hierarchies, attribute inheritance is not useful, which is why we required group hierarchies for dimension inheritance in netCDF-4. So I think the proposal should include a restriction to only hierarchical Group structures, which also has the desirable property that each Group, except for the root, has a unique parent Group. --Russ _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
