Identifies the reporting entity that originated the value in RegulatoryTradeID(1903). The reporting entity identifier may be assigned by a regulator or from a supported standard identifier source scheme.

In the context of CFTC usage for Unique Swap Identifier (USI), this field is required to convey the namespace of the entity creating the USI, in accordance to the USI Data Standard (https://www.cftc.gov/sites/default/files/idc/groups/public/@swaps/documents/dfsubmission/usidatastandards100112.pdf). For standardized identifier source schemes, such as the Unique Transaction Identifier (UTI), the source scheme is identified using supported code values.