Def - Data Type Master File Lookup
Master File Lookups, within the File Imports, are those that must match a pre-populated list of user-controlled values. In most Master File Imports, the value will be required to match the master file's unique value (most often the ID) but there are some master file values that can be added on-the-fly from the file import. In Transaction Imports, all master file values are required to match the master file's unique value.