Cannot download NCSS point feature collection as netcdf classic

[dopplershift]

Trying to access a point feature collection through NCSS with "accept=netcdf" results in a 400 with:

IllegalArgumentException: unknown DataType == uint

Here's a sample access url: http://thredds-test.unidata.ucar.edu/thredds/ncss/point/irma/metar/Metar_Station_Data_-_IRMA_fc.cdmr?var=altimeter_setting&var=wind_direction&var=dewpoint&var=sky_coverage&var=temperature&var=wind_speed&time=2017-09-10T12%3A00%3A00&west=-90&east=-80&south=24&north=34&accept=netcdf

This is on TDS 5.

[DennisHeimbigner]

Can you provide the catalog entry for that dataset? Since uint is not part of netcdf-3, we need to see why it is being generated.

[dopplershift]

https://github.com/Unidata/TdsConfig/blob/0630a198b38d8a092c3dc5f0ac3877ad7f250804/threddsTest/casestudies/catalog.xml#L198-L242

[lesserwhirls]

I think the problem here is the following. The netCDF file on the server is netCDF-4 and actually has uint data. However, the CF Point Writer code does not have the functionality to use the _Unsigned attribute convention so that the data can be encoded in netCDF-3. Just a WAG - not verified.