You can suggest a numeric code too, but the EPIC project may select a different code. The numeric codes in the official EPIC key file will range from 0-9000. You can use a numeric code from 9001-9999 locally for testing, without conflicting with the official key file. If they are included in the data file, they should be written only into netCDF files, and the numeric variable code should be omitted. We can't do all this perfectly, since many entries are tied to older files created in the past, with imperfectly selected keycodes, but we can try to be sure there is some logic to what we do now.
Comments are welcome.