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 the 338$b (or 337$a & 338$a) to determine which instanceFormatId to include in the JSON doc that will be POSTed via API. - 6/5/2020