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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Harvey, I appreciate your comments on the usefulness of dimension lengths of zero. As you pointed out, in netCDF-3, the unlimited dimension is permitted to have zero length to indicate no records have been written, and in netCDF-4 multiple unlimited dimensions will be permitted, any or all of which can have a length of zero. It would be difficult to further generalize this to cover fixed-size dimensions as well. Sometimes early designs and backward compatibility constraints together make some kinds of otherwise desirable changes impractical, even if they appear to be desirable. This is one of those cases, since there are lots of existing applications that equate specifying a dimension size of zero with defining an unlimited dimension, so I think netCDF-4 must be backward compatible with netCDF-3 in this respect. For a close analogy, see Guido van Rossum's article comparing how fiction authors and language designers paint themselves into a corner in their early work in his "The Harry Potter Theory of Programming Language Design": http://www.artima.com/weblogs/viewpost.jsp?thread=123234 --Russ
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