iNTERFACEWARE™ Inc.

Level 4

Sub-fields may be nested at one additional level, here named sub-sub-fields. Fourth level delimitation distinguishes between sub-sub-fields in sub-fields. The delimiter can be either permanently defined in the character column of the table above or can be taken from message header (position 7 for HL7). HL7 specifies the usage of '& at this level, but not many implementations really adhere to this recommendation.