The value of such a field follows the formatting rules for an ST field except that it is drawn from a table of legal values. There shall be an HL7 table number associated with ID data types. An examples of an ID field is OBR-25-result status. This data type should be used only for HL7 tables (see Section 2.7.6, "Table"). The reverse is not true, since in some circumstances it is more appropriate to use the CE data type for HL7 tables.
Primitive Type
This is a primitive data type with no internal structure. It represents a single value.