These are in the instanceFormats db table.
They are actually RDA Carrier Types and have just been loaded via API with /opt/folio/api/POST/instanceFormats.pl.
When loading titles (instances) it will be necessary to look at 338$b to determine which instanceFormatId(s) to include in the JSON doc that will be POSTed via API. If there is no 338 it can be left out of the JSON doc. - 6/5/2020