The Demo site for our new HL7 Version 2+ (plus) Standard
visit the hl7 website

Draft Website - For Review Purposes Only

HD - hierarchic designator

HL7 Component Table - HD - hierarchic designator
Seq# Description Data Type Usage Vocabulary Length C.LEN Flags
HD
1 Namespace ID IS O
0300 Namespace ID
 20
2 Universal ID ST C
199
3 Universal ID Type ID C
0301(S) Universal ID Type(Suggested)
[1..6]    

Components: <Namespace ID (IS)> & <Universal ID (ST)> & <Universal ID Type (ID)>


Examples:

Example 1: ISO example with only the 2nd and 3rd components valued:

|^2.16.840.1.113883.19^ISO|

The syntax of the second component is defined by the ISO standard for object identifiers, not by HL7 (for which the second component is of the ST data type). Thus the periods (".") in the second component are part of the ISO syntax, and are legal by the definition of the HL7 ST data type.

Example 2: A UUID example

|^478A0114-EBF0-7701-A023-6841FF05731A^UUID|

Example 3: A DNS example

|^falcon.iupui.edu^DNS|

Local examples:

Example 4: Local use only: a HD that looks like an IS data type

|LAB1|

|RX.PIMS.SystemB.KP.CA.SCA|

Note that the syntax of the first component is not defined by HL7 but by the site according to its own needs: the only requirement is that the first component’s structure is allowed by the HL7 string (ST) data type, which is used for values by the IS data type.

Example 5: Local identifier using components 2 and 3 only (Deprecated as of v2.8 and will be withdrawn in V2.10)

|^RX.PIMS.SystemB.CA.SCA^M|

An alternate way to encode the previous example, illustrating the use of the third component value of "M" (see HL7 Table 0301 - Universal ID type below) to identify a locally-defined identifier set. The second component has the same value as the previous example but is now defined to be a member of a set of allowable values defined by a site for the identifier set “M”. The use of local coding schemes as Universal ID Types is deprecated as of v 2.8; assigning authorities should be identified with true Universal IDs.

Example 6: local identifier and universal ID types:

|LAB1^2.16.840.1.113883.19.1.2.3.3.4.6.7^ISO|

A HD with an ISO "object Identifier" as a UID and a locally defined system name. Both the first component and the second and third (taken together) refer to the same entity. This example shows that the local value and the universal ID value may be transmitted with a single HD field.

HD-1: Namespace ID (IS)

Definition: The local coded item for the entity. The component intentionally remains associated with the IS data type in v 2.7.

User-defined Table 0300 - Namespace ID is used as the HL7 identifier for the user-defined table of values for this component.

Note: When the HD is used in a given segment (either as a field or as a component of another data type) this table may be re-defined (given a different user-defined table number and name) by the technical committee responsible for that segment.


HD-2: Universal ID (ST)

Definition: The HD’s second component, <universal ID> (UID), is a string formatted according to the scheme defined by the third component, <universal ID type> (UID type). The UID is intended to be unique over time within the UID type. It is rigorously defined. Each UID must belong to one of the specifically enumerated schemes for constructing UIDs (defined by the UID type). The UID (second component) must follow the syntactic rules of the particular universal identifier scheme (defined by the third component).

Note: These syntactic rules are not defined within HL7 but are defined by the rules of the particular universal identifier scheme (defined by the third component).


HD-3: Universal ID Type (ID)

Definition: The third component governs the interpretation of the second component of the HD. If the third component is a known UID refer to HL7 Table 0301 - Universal ID type for valid values, then the second component is a universal ID of that type.