another answer from Russ Rew:
> I can't help but wonder why arrays of numbers are allowed, but not strings --
> seems that strings are
> the more obvious usage for attribute values.
A property of netCDF data is that a file created by the interface in
one language, for example Java, should be readable by the API of any
other language, for example Fortran-77. The latter language doesn't
actually support variable-length strings, so it's difficult to write
an API for Fortran-77 that could deal with attributes that were arrays
of variable-length strings.
Many of the netCDF's limitations derive from the requirement that
Fortran-77 programs must be able to read all netCDF datasets.