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For the meaning of the various Product Definition Template numbers see http://apps.ecmwf.int/codes/grib/format/grib2/templates/4/.
You can also click on each entry to see the keys (contents) of the particular template e.g. For template 11, see https://apps.ecmwf.int/codes/grib/format/grib2/templates/4/11.
To view these templates in ecCodes, go to the grib2 definitions directory (this can be found via the "codes_info" command) and look for files named: template.4.*def
Some of these will include other template files. Let's look at one example of the template numbers 8 and 11:
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