Dear Bryan (and Steve) Thanks for your diagram and comments. Yes, it would be good to sit down with you and see if we can reconcile our views expressed in words and pictures. :-) We can talk about that in other emails so that CF doesn't have to join in the discussion of our diaries.
I may be disagreeing somewhat with you and Steve about whether the netCDF model should restrict us. It is where we started, but we may have constructed a logical model which has some more abstract concepts than netCDF does. For example, in netCDF we associate a dimension and a (Unidata) coord var by the equality of their names. In the CF model, the dimension and its coord var are part of the same thing, not two things with the same name. That is implied by your diagram too, which doesn't show "dimensions" on it. Also, in my model I have lumped together some things which CF does in different ways. For instance, I suggest that non-scalar formula terms are really auxiliary coord vars, and scalar coord vars and size-one coord vars are the same sort of thing. These are just my suggestions, which I am making because I think it might help how we think about further developments, including the representation of CF in other file formats (as you say), and the use of CF as a data model in an OO language. > - I don't like the concept of a space construct. It's a new term to me > which doesn't carry any useful attributes. I much prefer the use of > object, which *is* a language neutral term (in data modelling). You don't like the term or you don't like the concept? If "object" is a language-neutral term, I'm happy to call it a "space object" instead. It corresponds to a data variable, but I don't call it that because I think everything in the logical model - all the metadata and the coordinates - are part of it. So it is data and the space in which the data resides. But if you haven't yet filled in the data, it is just the space. It is possible in memory that you might have a space object with no data array in it, but by the time you write it out to a CF-netCDF file, you must have a data variable. > -I don't like central assumptions that are violated. Either we make it > or we don't. You can make that assumption property of some attributes of > space constructs. That is a good point. I suppose it means there is a higher level, perhaps a fragile and optional one, which relates some of the space objects. A higher level would also be needed to relate staggered grids and construct supergrids, as suggested by Balaji, but this hasn't been done in CF-netCDF yet. > - I think text without pictures is just as unhelpful as pictures without > text (my version :-). Let's see what we can do about that together. Best wishes Jonathan _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
