Their processing is specified in the program rather than by the tag table.
TYPE is a full-text searchable field that contains the translation of the record type code.
An error is signaled if the code is not found on the table. MARC TAG 001 Map the 001 as-is to M001. Also, at least one byte must be numeric. If no numerics are found, the PD does not get loaded. PD is a searchable, limitable field.