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All,May I request that Netcdf names beginning with a digit be handled as a special exception, requiring some kind of permission mode to be set before the API will allow these variables to be created? In this way the default behavior for most users would be the same as in previous versions.
I think it is generally desirable to have Netcdf names follow the same rigor and restrictions as variable names in common programming languages. Indeed Fortran, NCL, C/C++, Grads, and one or more Netcdf conventions all require the first character alphabetic or sometimes underscore. The original authors of the Netcdf specs had something like this in mind when they formalized this restriction.
Now I think the alpha restriction is important in practice for several diffuse reasons. Primarily, it will reduce compatibility problems over time between producers and consumers of Netcdf data, because of conventions. Also, it's common practice to copy variable names between files and program code, aiding clarity. Also, the occurrence of non-letters at the start of a name can be helpful as an early warning of malfunctions.
In summary, I request the creation of a non-default exception mode to take care of applications like ncl_convert2nc. The documentation should retain the traditional restriction to letters and underscore only. The use of leading digits and the exception mode should also be documented but called "deprecated".
I see this as a small amount of work now to save more in distributed problems later. Thanks for your consideration.
Dave Allured CU/CIRES Climate Diagnostics Center (CDC) http://cires.colorado.edu/science/centers/cdc/ NOAA/ESRL/PSD, Climate Analysis Branch (CAB) http://www.cdc.noaa.gov/ Ed Hartnett wrote on June 18:
David Brown <dbrown@xxxxxxxx> writes:Hi,When we recently relinked our software products, NCL and PyNIO, with the newly released version of the NetCDF 4.0 library we discovered that there seems to have been a change in the actual, as opposed to the documented, rules for variable names. Specifically it appears that names that begin with a digit can no longerbe written to NetCDF files.Howdy All! As David points out, creating names beginning with a digit are no longer allowed in version 3.6.3 and version 4.0. This is in accordance with the documented rules, but was never enforced in previous versions. We are changing the code (and the documentation) so that names beginning with a digit are allowed again. Users should note that such names also violate the CF conventions, and possibly other conventions. I'll announce here when the code has been changed, and those who need to create objects with names that begin with a digit can grab the daily snapshot. Thanks, Ed
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