[netcdf-java] Mime types for netCDF 3/4

Hello,

an earlier thread was asking about the official netCDF mime type:
http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2013/msg00128.html.
This is pretty straightforward, but not as clear when it relates to netCDF
4.  I use web services that need to both advertise file formats through a
mime type as well as allow for data to be requested in a variety of formats
through a mime type.  Is there a suggested way of discriminating between
netCDF 3 and 4 through mime types?

Aaron