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HL7 Segment Browser

Browse all common HL7 v2.x segments with field definitions and message type schemas. Free reference for healthcare integration analysts.

This tool contains only public HL7 standard definitions. No HL7 messages or patient data are processed.

21 segments

Segment Description Fields

AIG Appointment Information - General Resource 14

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - AIG	`SI`	—	✓	—
2	Segment Action Code	`ID`	3	—	—
3	Resource ID	`CWE`	—	—	—
4	Resource Type	`CWE`	—	✓	—
5	Resource Group	`CWE`	—	—	✓
6	Resource Quantity	`NM`	—	—	—
7	Resource Quantity Units	`CE`	—	—	—
8	Start Date/Time	`TS`	—	—	—
9	Start Date/Time Offset	`NM`	—	—	—
10	Start Date/Time Offset Units	`CE`	—	—	—
11	Duration	`NM`	—	—	—
12	Duration Units	`CE`	—	—	—
13	Allow Substitution Code	`IS`	10	—	—
14	Filler Status Code	`CE`	—	—	—

AIL Appointment Information - Location Resource 12

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - AIL	`SI`	—	✓	—
2	Segment Action Code	`ID`	3	—	—
3	Location Resource ID	`PL`	—	—	✓
4	Location Type - AIL	`CWE`	—	—	—
5	Location Group	`CE`	—	—	—
6	Start Date/Time	`TS`	—	—	—
7	Start Date/Time Offset	`NM`	—	—	—
8	Start Date/Time Offset Units	`CE`	—	—	—
9	Duration	`NM`	—	—	—
10	Duration Units	`CE`	—	—	—
11	Allow Substitution Code	`IS`	10	—	—
12	Filler Status Code	`CE`	—	—	—

AIP Appointment Information - Personnel Resource 12

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - AIP	`SI`	—	✓	—
2	Segment Action Code	`ID`	3	—	—
3	Personnel Resource ID	`XCN`	—	—	✓
4	Resource Type	`CWE`	—	—	—
5	Resource Group	`CWE`	—	—	—
6	Start Date/Time	`TS`	—	—	—
7	Start Date/Time Offset	`NM`	—	—	—
8	Start Date/Time Offset Units	`CE`	—	—	—
9	Duration	`NM`	—	—	—
10	Duration Units	`CE`	—	—	—
11	Allow Substitution Code	`IS`	10	—	—
12	Filler Status Code	`CE`	—	—	—

AL1 Allergy Information 6

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - AL1	`SI`	—	✓	—
2	Allergen Type Code	`CE`	—	—	—
3	Allergen Code/Mnemonic/Description	`CE`	—	✓	—
4	Allergy Severity Code	`CE`	—	—	—
5	Allergy Reaction Code	`ST`	15	—	✓
6	Identification Date	`DT`	—	—	—

DG1 Diagnosis 21

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - DG1	`SI`	—	✓	—
2	Diagnosis Coding Method	`ID`	2	—	—
3	Diagnosis Code - DG1	`CE`	—	—	—
4	Diagnosis Description	`ST`	40	—	—
5	Diagnosis Date/Time	`TS`	—	—	—
6	Diagnosis Type	`IS`	2	✓	—
7	Major Diagnostic Category	`CE`	—	—	—
8	Diagnostic Related Group	`CE`	—	—	—
9	DRG Approval Indicator	`ID`	2	—	—
10	DRG Grouper Review Code	`IS`	2	—	—
11	Outlier Type	`CE`	—	—	—
12	Outlier Days	`NM`	—	—	—
13	Outlier Cost	`CP`	—	—	—
14	Grouper Version And Type	`ST`	4	—	—
15	Diagnosis Priority	`ID`	2	—	—
16	Diagnosing Clinician	`XCN`	—	—	✓
17	Diagnosis Classification	`IS`	3	—	—
18	Confidential Indicator	`ID`	1	—	—
19	Attestation Date/Time	`TS`	—	—	—
20	Diagnosis Identifier	`EI`	—	—	—
21	Diagnosis Action Code	`ID`	1	—	—

EVN Event Type 7

#	Field Name	Type	Max Len	Req	Rep
1	Event Type Code	`ID`	3	—	—
2	Recorded Date/Time	`TS`	—	✓	—
3	Date/Time Planned Event	`TS`	—	—	—
4	Event Reason Code	`IS`	3	—	—
5	Operator ID	`XCN`	—	—	✓
6	Event Occurred	`TS`	—	—	—
7	Event Facility	`HD`	—	—	—

FT1 Financial Transaction 31

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - FT1	`SI`	—	—	—
2	Transaction ID	`ST`	12	—	—
3	Transaction Batch ID	`ST`	10	—	—
4	Transaction Date	`DR`	—	✓	—
5	Transaction Posting Date	`TS`	—	—	—
6	Transaction Type	`IS`	8	✓	—
7	Transaction Code	`CE`	—	✓	—
8	Transaction Description	`ST`	40	—	—
9	Transaction Description - Alternative	`ST`	40	—	—
10	Transaction Quantity	`NM`	—	—	—
11	Transaction Amount - Extended	`CP`	—	—	—
12	Transaction Amount - Unit	`CP`	—	—	—
13	Department Code	`CE`	—	—	—
14	Insurance Plan ID	`CE`	—	—	✓
15	Insurance Amount	`CP`	—	—	—
16	Assigned Patient Location	`PL`	—	—	—
17	Fee Schedule	`IS`	1	—	—
18	Patient Type	`IS`	2	—	—
19	Diagnosis Code - FT1	`CE`	—	—	✓
20	Performed By Code	`XCN`	—	—	✓
21	Ordered By Code	`XCN`	—	—	✓
22	Unit Cost	`CP`	—	—	—
23	Filler Order Number	`EI`	—	—	—
24	Entered By Code	`XCN`	—	—	✓
25	Procedure Code	`CE`	—	—	—
26	Procedure Code Modifier	`CE`	—	—	✓
27	Advanced Beneficiary Notice Code	`CE`	—	—	—
28	Medically Necessary Duplicate Procedure Reason	`CWE`	—	—	—
29	NDC Code	`CWE`	—	—	—
30	Payment Reference ID	`CX`	—	—	—
31	Transaction Reference Key	`SI`	—	—	✓

GT1 Guarantor 30

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - GT1	`SI`	—	✓	—
2	Guarantor Number	`CX`	—	—	✓
3	Guarantor Name	`XPN`	—	✓	✓
4	Guarantor Spouse Name	`XPN`	—	—	✓
5	Guarantor Address	`XAD`	—	—	✓
6	Guarantor Ph Num - Home	`XTN`	—	—	✓
7	Guarantor Ph Num - Business	`XTN`	—	—	✓
8	Guarantor Date/Time of Birth	`TS`	—	—	—
9	Guarantor Administrative Sex	`IS`	1	—	—
10	Guarantor Type	`IS`	2	—	—
11	Guarantor Relationship	`CE`	—	—	—
12	Guarantor SSN	`ST`	11	—	—
13	Guarantor Date - Begin	`DT`	—	—	—
14	Guarantor Date - End	`DT`	—	—	—
15	Guarantor Priority	`NM`	—	—	—
16	Guarantor Employer Name	`XPN`	—	—	✓
17	Guarantor Employer Address	`XAD`	—	—	✓
18	Guarantor Employer Phone Number	`XTN`	—	—	✓
19	Guarantor Employee ID Number	`CX`	—	—	✓
20	Guarantor Employment Status	`IS`	2	—	—
21	Guarantor Organization Name	`XON`	—	—	✓
22	Guarantor Billing Hold Flag	`ID`	1	—	—
23	Guarantor Credit Rating Code	`CE`	—	—	—
24	Guarantor Death Date And Time	`TS`	—	—	—
25	Guarantor Death Flag	`ID`	1	—	—
26	Guarantor Charge Adjustment Code	`CE`	—	—	—
27	Guarantor Household Annual Income	`CP`	—	—	—
28	Guarantor Household Size	`NM`	—	—	—
29	Guarantor Employer ID Number	`CX`	—	—	✓
30	Guarantor Marital Status Code	`CE`	—	—	—

IN1 Insurance 49

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - IN1	`SI`	—	✓	—
2	Insurance Plan ID	`CE`	—	✓	—
3	Insurance Company ID	`CX`	—	✓	✓
4	Insurance Company Name	`XON`	—	—	✓
5	Insurance Company Address	`XAD`	—	—	✓
6	Insurance Company Contact Person	`XPN`	—	—	✓
7	Insurance Company Phone Number	`XTN`	—	—	✓
8	Group Number	`ST`	12	—	—
9	Group Name	`XON`	—	—	✓
10	Insured's Group Emp ID	`CX`	—	—	✓
11	Insured's Group Emp Name	`XON`	—	—	✓
12	Plan Effective Date	`DT`	—	—	—
13	Plan Expiration Date	`DT`	—	—	—
14	Authorization Information	`AUI`	—	—	—
15	Plan Type	`IS`	3	—	—
16	Name of Insured	`XPN`	—	—	✓
17	Insured's Relationship to Patient	`CE`	—	—	—
18	Insured's Date of Birth	`TS`	—	—	—
19	Insured's Address	`XAD`	—	—	✓
20	Assignment of Benefits	`IS`	2	—	—
21	Coordination of Benefits	`IS`	2	—	—
22	Coord of Ben. Priority	`ST`	2	—	—
23	Notice of Admission Flag	`ID`	1	—	—
24	Notice of Admission Date	`DT`	—	—	—
25	Report of Eligibility Flag	`ID`	1	—	—
26	Report of Eligibility Date	`DT`	—	—	—
27	Release Information Code	`IS`	2	—	—
28	Pre-Admit Cert (PAC)	`ST`	15	—	—
29	Verification Date/Time	`TS`	—	—	—
30	Verification By	`XCN`	—	—	✓
31	Type of Agreement Code	`IS`	2	—	—
32	Billing Status	`IS`	2	—	—
33	Lifetime Reserve Days	`NM`	—	—	—
34	Delay Before L.R. Day	`NM`	—	—	—
35	Company Plan Code	`IS`	8	—	—
36	Policy Number	`ST`	15	—	—
37	Policy Deductible	`CP`	—	—	—
38	Policy Limit - Amount	`CP`	—	—	—
39	Policy Limit - Days	`NM`	—	—	—
40	Room Rate - Semi-Private	`CP`	—	—	—
41	Room Rate - Private	`CP`	—	—	—
42	Insured's Employment Status	`CE`	—	—	—
43	Insured's Administrative Sex	`IS`	1	—	—
44	Insured's Employer's Address	`XAD`	—	—	✓
45	Verification Status	`ST`	2	—	—
46	Prior Insurance Plan ID	`IS`	8	—	—
47	Coverage Type	`IS`	3	—	—
48	Handicap	`IS`	2	—	—
49	Insured's ID Number	`CX`	—	—	✓

MSA Message Acknowledgment 6

#	Field Name	Type	Max Len	Req	Rep
1	Acknowledgment Code	`ID`	2	✓	—
2	Message Control ID	`ST`	20	✓	—
3	Text Message	`ST`	80	—	—
4	Expected Sequence Number	`NM`	—	—	—
5	Delayed Acknowledgment Type	`ID`	1	—	—
6	Error Condition	`CE`	—	—	—

MSH Message Header 21

#	Field Name	Type	Max Len	Req	Rep
1	Field Separator	`ST`	1	✓	—
2	Encoding Characters	`ST`	4	✓	—
3	Sending Application	`HD`	—	—	—
4	Sending Facility	`HD`	—	—	—
5	Receiving Application	`HD`	—	—	—
6	Receiving Facility	`HD`	—	—	—
7	Date/Time of Message	`TS`	—	✓	—
8	Security	`ST`	40	—	—
9	Message Type	`MSG`	—	✓	—
10	Message Control ID	`ST`	20	✓	—
11	Processing ID	`PT`	—	✓	—
12	Version ID	`VID`	—	✓	—
13	Sequence Number	`NM`	—	—	—
14	Continuation Pointer	`ST`	180	—	—
15	Accept Acknowledgment Type	`ID`	2	—	—
16	Application Acknowledgment Type	`ID`	2	—	—
17	Country Code	`ID`	3	—	—
18	Character Set	`ID`	16	—	✓
19	Principal Language of Message	`CE`	—	—	—
20	Alternate Character Set Handling Scheme	`ID`	20	—	—
21	Message Profile Identifier	`EI`	—	—	✓

NK1 Next of Kin / Associated Parties 40

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - NK1	`SI`	—	✓	—
2	Name	`XPN`	—	—	✓
3	Relationship	`CE`	—	—	—
4	Address	`XAD`	—	—	✓
5	Phone Number	`XTN`	—	—	✓
6	Business Phone Number	`XTN`	—	—	✓
7	Contact Role	`CE`	—	—	—
8	Start Date	`DT`	—	—	—
9	End Date	`DT`	—	—	—
10	Next of Kin / Associated Parties Job Title	`ST`	60	—	—
11	Next of Kin / Associated Parties Job Code/Class	`JCC`	—	—	—
12	Next of Kin / Associated Parties Employee Number	`CX`	—	—	—
13	Organization Name - NK1	`XON`	—	—	✓
14	Marital Status	`CE`	—	—	—
15	Administrative Sex	`IS`	1	—	—
16	Date/Time of Birth	`TS`	—	—	—
17	Living Dependency	`IS`	2	—	✓
18	Ambulatory Status	`IS`	2	—	✓
19	Citizenship	`CE`	—	—	✓
20	Primary Language	`CE`	—	—	—
21	Living Arrangement	`IS`	2	—	—
22	Publicity Code	`CE`	—	—	—
23	Protection Indicator	`ID`	1	—	—
24	Student Indicator	`IS`	2	—	—
25	Religion	`CE`	—	—	—
26	Mother's Maiden Name	`XPN`	—	—	✓
27	Nationality	`CE`	—	—	—
28	Ethnic Group	`CE`	—	—	✓
29	Contact Reason	`CE`	—	—	✓
30	Contact Person's Name	`XPN`	—	—	✓
31	Contact Person's Telephone Number	`XTN`	—	—	✓
32	Contact Person's Address	`XAD`	—	—	✓
33	Next of Kin/Associated Party's Identifiers	`CX`	—	—	✓
34	Job Status	`IS`	2	—	—
35	Race	`CE`	—	—	✓
36	Handicap	`IS`	2	—	—
37	Contact Person Social Security Number	`ST`	16	—	—
38	Next of Kin Birth Place	`ST`	250	—	—
39	VIP Indicator	`IS`	2	—	—
40	Next of Kin Telecommunication Information	`XTN`	—	—	—

NTE Notes and Comments 4

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - NTE	`SI`	—	—	—
2	Source of Comment	`ID`	8	—	—
3	Comment	`FT`	—	—	✓
4	Comment Type	`CE`	—	—	—

OBR Observation Request 45

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - OBR	`SI`	—	—	—
2	Placer Order Number	`EI`	—	—	—
3	Filler Order Number	`EI`	—	—	—
4	Universal Service Identifier	`CE`	—	✓	—
5	Priority	`ID`	2	—	—
6	Requested Date/Time	`TS`	—	—	—
7	Observation Date/Time	`TS`	—	—	—
8	Observation End Date/Time	`TS`	—	—	—
9	Collection Volume	`CQ`	—	—	—
10	Collector Identifier	`XCN`	—	—	✓
11	Specimen Action Code	`ID`	1	—	—
12	Danger Code	`CE`	—	—	—
13	Relevant Clinical Information	`ST`	300	—	—
14	Specimen Received Date/Time	`TS`	—	—	—
15	Specimen Source	`SPS`	—	—	—
16	Ordering Provider	`XCN`	—	—	✓
17	Order Callback Phone Number	`XTN`	—	—	✓
18	Placer Field 1	`ST`	60	—	—
19	Placer Field 2	`ST`	60	—	—
20	Filler Field 1	`ST`	60	—	—
21	Filler Field 2	`ST`	60	—	—
22	Results Rpt/Status Chng Date/Time	`TS`	—	—	—
23	Charge to Practice	`MOC`	—	—	—
24	Diagnostic Serv Sect ID	`ID`	10	—	—
25	Result Status	`ID`	1	—	—
26	Parent Result	`PRL`	—	—	—
27	Quantity/Timing	`TQ`	—	—	✓
28	Result Copies To	`XCN`	—	—	✓
29	Parent	`EIP`	—	—	—
30	Transportation Mode	`ID`	20	—	—
31	Reason for Study	`CE`	—	—	✓
32	Principal Result Interpreter	`NDL`	—	—	—
33	Assistant Result Interpreter	`NDL`	—	—	✓
34	Technician	`NDL`	—	—	✓
35	Transcriptionist	`NDL`	—	—	✓
36	Scheduled Date/Time	`TS`	—	—	—
37	Number of Sample Containers	`NM`	—	—	—
38	Transport Logistics of Collected Sample	`CE`	—	—	✓
39	Collector's Comment	`CE`	—	—	✓
40	Transport Arrangement Responsibility	`CE`	—	—	—
41	Transport Arranged	`ID`	30	—	—
42	Escort Required	`ID`	1	—	—
43	Planned Patient Transport Comment	`CE`	—	—	✓
44	Procedure Code	`CE`	—	—	—
45	Procedure Code Modifier	`CE`	—	—	✓

OBX Observation/Result 25

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - OBX	`SI`	—	—	—
2	Value Type	`ID`	2	—	—
3	Observation Identifier	`CE`	—	✓	—
4	Observation Sub-ID	`ST`	20	—	—
5	Observation Value	`Varies`	—	—	✓
6	Units	`CE`	—	—	—
7	References Range	`ST`	60	—	—
8	Abnormal Flags	`IS`	5	—	✓
9	Probability	`NM`	—	—	—
10	Nature of Abnormal Test	`ID`	2	—	✓
11	Observation Result Status	`ID`	1	✓	—
12	Effective Date of Reference Range Values	`TS`	—	—	—
13	User Defined Access Checks	`ST`	20	—	—
14	Date/Time of Observation	`TS`	—	—	—
15	Producer's Reference	`CE`	—	—	—
16	Responsible Observer	`XCN`	—	—	✓
17	Observation Method	`CE`	—	—	✓
18	Equipment Instance Identifier	`EI`	—	—	✓
19	Date/Time of Analysis	`TS`	—	—	—
20	Reserved (OBX-20)	`ST`	—	—	—
21	Reserved (OBX-21)	`ST`	—	—	—
22	Reserved (OBX-22)	`ST`	—	—	—
23	Reserved (OBX-23)	`ST`	—	—	—
24	Performing Organization Name	`XON`	—	—	—
25	Performing Organization Address	`XAD`	—	—	—

ORC Common Order 31

#	Field Name	Type	Max Len	Req	Rep
1	Order Control	`ID`	2	✓	—
2	Placer Order Number	`EI`	—	—	—
3	Filler Order Number	`EI`	—	—	—
4	Placer Group Number	`EI`	—	—	—
5	Order Status	`ID`	2	—	—
6	Response Flag	`ID`	1	—	—
7	Quantity/Timing	`TQ`	—	—	✓
8	Parent	`EIP`	—	—	—
9	Date/Time of Transaction	`TS`	—	—	—
10	Entered By	`XCN`	—	—	✓
11	Verified By	`XCN`	—	—	✓
12	Ordering Provider	`XCN`	—	—	✓
13	Enterer's Location	`PL`	—	—	—
14	Call Back Phone Number	`XTN`	—	—	✓
15	Order Effective Date/Time	`TS`	—	—	—
16	Order Control Code Reason	`CE`	—	—	—
17	Entering Organization	`CE`	—	—	—
18	Entering Device	`CE`	—	—	—
19	Action By	`XCN`	—	—	✓
20	Advanced Beneficiary Notice Code	`CE`	—	—	—
21	Ordering Facility Name	`XON`	—	—	✓
22	Ordering Facility Address	`XAD`	—	—	✓
23	Ordering Facility Phone Number	`XTN`	—	—	✓
24	Ordering Provider Address	`XAD`	—	—	✓
25	Order Status Modifier	`CWE`	—	—	—
26	Advanced Beneficiary Notice Override Reason	`CWE`	—	—	—
27	Filler's Expected Availability Date/Time	`TS`	—	—	—
28	Confidentiality Code	`CWE`	—	—	—
29	Order Type	`CWE`	—	—	—
30	Enterer Authorization Mode	`CNE`	—	—	—
31	Parent Universal Service Identifier	`CWE`	—	—	—

PID Patient Identification 39

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - PID	`SI`	—	—	—
2	Patient ID (External)	`CX`	—	—	—
3	Patient Identifier List	`CX`	—	✓	✓
4	Alternate Patient ID - PID	`CX`	—	—	✓
5	Patient Name	`XPN`	—	✓	✓
6	Mother's Maiden Name	`XPN`	—	—	✓
7	Date/Time of Birth	`TS`	—	—	—
8	Administrative Sex	`IS`	1	—	—
9	Patient Alias	`XPN`	—	—	✓
10	Race	`CE`	—	—	✓
11	Patient Address	`XAD`	—	—	✓
12	County Code	`IS`	4	—	—
13	Phone Number - Home	`XTN`	—	—	✓
14	Phone Number - Business	`XTN`	—	—	✓
15	Primary Language	`CE`	—	—	—
16	Marital Status	`CE`	—	—	—
17	Religion	`CE`	—	—	—
18	Patient Account Number	`CX`	—	—	—
19	SSN Number - Patient	`ST`	16	—	—
20	Driver's License Number - Patient	`DLN`	—	—	—
21	Mother's Identifier	`CX`	—	—	✓
22	Ethnic Group	`CE`	—	—	✓
23	Birth Place	`ST`	250	—	—
24	Multiple Birth Indicator	`ID`	1	—	—
25	Birth Order	`NM`	—	—	—
26	Citizenship	`CE`	—	—	✓
27	Veterans Military Status	`CE`	—	—	—
28	Nationality	`CE`	—	—	—
29	Patient Death Date and Time	`TS`	—	—	—
30	Patient Death Indicator	`ID`	1	—	—
31	Identity Unknown Indicator	`ID`	1	—	—
32	Identity Reliability Code	`IS`	20	—	✓
33	Last Update Date/Time	`TS`	—	—	—
34	Last Update Facility	`HD`	—	—	—
35	Species Code	`CE`	—	—	—
36	Breed Code	`CE`	—	—	—
37	Strain	`ST`	80	—	—
38	Production Class Code	`CE`	—	—	—
39	Tribal Citizenship	`CWE`	—	—	✓

PV1 Patient Visit 52

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - PV1	`SI`	—	—	—
2	Patient Class	`IS`	1	✓	—
3	Assigned Patient Location	`PL`	—	—	—
4	Admission Type	`IS`	2	—	—
5	Preadmit Number	`CX`	—	—	—
6	Prior Patient Location	`PL`	—	—	—
7	Attending Doctor	`XCN`	—	—	✓
8	Referring Doctor	`XCN`	—	—	✓
9	Consulting Doctor	`XCN`	—	—	✓
10	Hospital Service	`IS`	3	—	—
11	Temporary Location	`PL`	—	—	—
12	Preadmit Test Indicator	`IS`	2	—	—
13	Re-admission Indicator	`IS`	2	—	—
14	Admit Source	`IS`	6	—	—
15	Ambulatory Status	`IS`	2	—	✓
16	VIP Indicator	`IS`	2	—	—
17	Admitting Doctor	`XCN`	—	—	✓
18	Patient Type	`IS`	2	—	—
19	Visit Number	`CX`	—	—	—
20	Financial Class	`FC`	—	—	✓
21	Charge Price Indicator	`IS`	2	—	—
22	Courtesy Code	`IS`	2	—	—
23	Credit Rating	`IS`	2	—	—
24	Contract Code	`IS`	2	—	✓
25	Contract Effective Date	`DT`	—	—	✓
26	Contract Amount	`NM`	—	—	✓
27	Contract Period	`NM`	—	—	✓
28	Interest Code	`IS`	2	—	—
29	Transfer to Bad Debt Code	`IS`	4	—	—
30	Transfer to Bad Debt Date	`DT`	—	—	—
31	Bad Debt Agency Code	`IS`	10	—	—
32	Bad Debt Transfer Amount	`NM`	—	—	—
33	Bad Debt Recovery Amount	`NM`	—	—	—
34	Delete Account Indicator	`IS`	1	—	—
35	Delete Account Date	`DT`	—	—	—
36	Discharge Disposition	`IS`	3	—	—
37	Discharged to Location	`DLD`	—	—	—
38	Diet Type	`CE`	—	—	—
39	Servicing Facility	`IS`	2	—	—
40	Bed Status	`IS`	1	—	—
41	Account Status	`IS`	2	—	—
42	Pending Location	`PL`	—	—	—
43	Prior Temporary Location	`PL`	—	—	—
44	Admit Date/Time	`TS`	—	—	—
45	Discharge Date/Time	`TS`	—	—	✓
46	Current Patient Balance	`NM`	—	—	—
47	Total Charges	`NM`	—	—	—
48	Total Adjustments	`NM`	—	—	—
49	Total Payments	`NM`	—	—	—
50	Alternate Visit ID	`CX`	—	—	—
51	Visit Indicator	`IS`	1	—	—
52	Other Healthcare Provider	`XCN`	—	—	✓

PV2 Patient Visit - Additional Information 30

#	Field Name	Type	Max Len	Req	Rep
1	Prior Pending Location	`PL`	—	—	—
2	Accommodation Code	`CE`	—	—	—
3	Admit Reason	`CE`	—	—	—
4	Transfer Reason	`CE`	—	—	—
5	Patient Valuables	`ST`	25	—	✓
6	Patient Valuables Location	`ST`	25	—	—
7	Visit User Code	`IS`	2	—	✓
8	Expected Admit Date/Time	`TS`	—	—	—
9	Expected Discharge Date/Time	`TS`	—	—	—
10	Estimated Length of Inpatient Stay	`NM`	—	—	—
11	Actual Length of Inpatient Stay	`NM`	—	—	—
12	Visit Description	`ST`	50	—	—
13	Referral Source Code	`XCN`	—	—	✓
14	Previous Service Date	`DT`	—	—	—
15	Employment Illness Related Indicator	`ID`	1	—	—
16	Purge Status Code	`IS`	1	—	—
17	Purge Status Date	`DT`	—	—	—
18	Special Program Code	`IS`	2	—	—
19	Retention Indicator	`ID`	1	—	—
20	Expected Number of Insurance Plans	`NM`	—	—	—
21	Visit Publicity Code	`CE`	—	—	—
22	Visit Protection Indicator	`ID`	1	—	—
23	Clinic Organization Name	`XON`	—	—	✓
24	Patient Status Code	`IS`	2	—	—
25	Visit Priority Code	`CE`	—	—	—
26	Previous Treatment Date	`DT`	—	—	—
27	Expected Insurance Plan ID	`CE`	—	—	✓
28	Word Processing Object	`ED`	—	—	—
29	Visit Caregiver ID	`XCN`	—	—	✓
30	Other Healthcare Provider	`XCN`	—	—	✓

SCH Scheduling Activity Information 27

#	Field Name	Type	Max Len	Req	Rep
1	Placer Appointment ID	`EI`	—	—	—
2	Filler Appointment ID	`EI`	—	—	—
3	Occurrence Number	`NM`	—	—	—
4	Placer Group Number	`EI`	—	—	—
5	Schedule ID	`CE`	—	—	—
6	Event Reason	`CE`	—	✓	—
7	Appointment Reason	`CE`	—	—	—
8	Appointment Type	`CE`	—	—	—
9	Appointment Duration	`NM`	—	—	—
10	Appointment Duration Units	`CE`	—	—	—
11	Appointment Timing Quantity	`TQ`	—	—	✓
12	Placer Contact Person	`XCN`	—	—	✓
13	Placer Contact Phone Number	`XTN`	—	—	—
14	Placer Contact Address	`XAD`	—	—	✓
15	Placer Contact Location	`PL`	—	—	—
16	Filler Contact Person	`XCN`	—	✓	✓
17	Filler Contact Phone Number	`XTN`	—	—	—
18	Filler Contact Address	`XAD`	—	—	✓
19	Filler Contact Location	`PL`	—	—	—
20	Entered by Person	`XCN`	—	✓	✓
21	Entered by Phone Number	`XTN`	—	—	✓
22	Entered by Location	`PL`	—	—	—
23	Parent Placer Appointment ID	`EI`	—	—	—
24	Parent Filler Appointment ID	`EI`	—	—	—
25	Filler Status Code	`CE`	—	—	—
26	Placer Order Number	`EI`	—	—	✓
27	Filler Order Number	`EI`	—	—	✓

TXA Transcription Document Header 23

#	Field Name	Type	Max Len	Req	Rep
1	Set ID - TXA	`SI`	—	✓	—
2	Document Type	`IS`	30	✓	—
3	Document Content Presentation	`ID`	2	—	—
4	Activity Date/Time	`TS`	—	—	—
5	Primary Activity Provider Code/Name	`XCN`	—	—	✓
6	Origination Date/Time	`TS`	—	—	—
7	Transcription Date/Time	`TS`	—	—	—
8	Edit Date/Time	`TS`	—	—	✓
9	Originator Code/Name	`XCN`	—	—	✓
10	Assigned Document Authenticator	`XCN`	—	—	✓
11	Transcriptionist Code/Name	`XCN`	—	—	✓
12	Unique Document Number	`EI`	—	✓	—
13	Parent Document Number	`EI`	—	—	—
14	Placer Order Number	`EI`	—	—	✓
15	Filler Order Number	`EI`	—	—	—
16	Unique Document File Name	`ST`	30	—	—
17	Document Completion Status	`ID`	2	✓	—
18	Document Confidentiality Status	`ID`	2	—	—
19	Document Availability Status	`ID`	2	—	—
20	Document Storage Status	`ID`	2	—	—
21	Document Change Reason	`ST`	30	—	—
22	Authentication Person, Time Stamp	`PPN`	—	—	✓
23	Distributed Copies	`XCN`	—	—	✓

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Required
	Next of Kin / Associated Parties	Optional
	Patient Visit - Additional Information	Optional
	Insurance	Optional
	Guarantor	Optional
	Allergy Information	Optional
	Diagnosis	Optional

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Required
	Next of Kin / Associated Parties	Optional
	Insurance	Optional

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Required
	Next of Kin / Associated Parties	Optional

Segment	Description	Usage
	Message Header	Required
	Patient Identification	Required
	Patient Visit	Optional
	Common Order	Required
	Observation Request	Required
	Notes and Comments	Optional

Segment	Description	Usage
	Message Header	Required
	Patient Identification	Required
	Patient Visit	Optional
	Common Order	Optional
	Observation Request	Required
	Observation/Result	Required
	Notes and Comments	Optional

Segment	Description	Usage
	Message Header	Required
	Scheduling Activity Information	Required
	Patient Identification	Required
	Patient Visit	Optional
	Appointment Information - General Resource	Optional
	Appointment Information - Location Resource	Optional
	Appointment Information - Personnel Resource	Optional

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Required
	Transcription Document Header	Required
	Observation/Result	Optional

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Required
	Diagnosis	Optional
	Insurance	Optional

Segment	Description	Usage
	Message Header	Required
	Event Type	Required
	Patient Identification	Required
	Patient Visit	Optional
	Financial Transaction	Required
	Diagnosis	Optional

Keywords

hl7 segment browserhl7 segment definitionshl7 v2 segmentshl7 field referencehl7 message typeshl7 integration referencehl7 schema browser

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How to use

On the Segments tab, browse all available HL7 v2.x segment definitions sorted alphabetically.

Click the expand button on any segment row to reveal its full field list — position, name, data type, max length, required, and repeating flags.

Use the search box to filter segments by code or description, or use the Data Type filter to show only segments containing a specific HL7 data type.

On the Message Types tab, browse the 10 most common HL7 v2.x message structures and click any message type to see its required and optional segments in sequence.

Click any segment code in the Message Types tab to jump directly to that segment's full field definition in the Segments tab, with automatic highlighting.

Features

21 Segments with Full Field Definitions

Covers all segments used in the 10 most common HL7 v2.x message types — ADT, ORM, ORU, SIU, MDM, BAR, DFT — with field positions, data types, max lengths, and required/repeating flags.

10 Message Type Schemas

Browse ADT^A01, ORU^R01, ORM^O01, SIU^S12, and 6 more message structures showing required vs. optional segment composition in the correct sequence.

Cross-Reference Navigation

Click a segment code in any message type schema to jump directly to its full field definition in the Segments tab, with automatic scroll and highlight.

Search and Data Type Filter

Filter segments by name or code, or narrow to segments containing a specific data type (CX, XPN, CE, TS) to quickly find relevant definitions.

Export to CSV

Download the currently visible segment list as a CSV file for use in mapping documents, interface specifications, or offline reference.

Why Choose This Tool?

Zero PHI Risk — Pure Standard Reference

Unlike the HL7 Viewer (which parses your actual messages), this tool contains only publicly available HL7 standard segment and message type definitions. There is nothing to upload, no patient data processed, and no network requests made. Healthcare IT teams can use it freely on hospital workstations, VPN-connected devices, and locked-down corporate networks without any data governance concerns.

Cross-Referenced Message Schemas

Knowing a segment's field definitions in isolation is useful — but knowing which messages require it is essential for interface work. The Message Types tab shows the composition of the 10 most common HL7 v2.x message structures, and clicking any segment code jumps directly to its full field definition. This cross-referencing eliminates the constant switching between reference documents that slows down interface analysis.

Faster Than the HL7 Specification PDF

The official HL7 v2.x specification runs to thousands of pages across multiple volumes. For everyday interface work — writing a mapping document, debugging a missing field, or checking a field's data type — most engineers need the segment table for MSH, PID, or OBX, not the full specification. This browser puts those definitions one search away instead of buried in a PDF.

Consistent With Our HL7 Viewer

The segment definitions in this browser are the same ones used by the HL7 Viewer when it annotates your messages with field names, data types, and required-field validation. If you spot an unexpected annotation in the viewer, you can look up the exact definition here. This consistency makes both tools more useful together.

Understanding HL7 v2.x Message Structure: A Reference for Integration Analysts

What Is HL7 v2.x?

HL7 version 2.x (often called HL7 v2 or HL7 2.x) is the dominant standard for electronic data interchange between healthcare information systems. Despite being more than 30 years old, it continues to carry the majority of clinical message traffic in hospitals worldwide — patient admissions, laboratory orders and results, scheduling events, financial transactions, and clinical documentation. Most hospital interface engines (Mirth Connect, Rhapsody, Ensemble, Cloverleaf) are still primarily routing HL7 v2.x messages.

The Anatomy of an HL7 v2.x Message

An HL7 v2.x message is a pipe-delimited text file where each line is a segment. Every segment starts with a three-letter code (e.g., MSH, PID, OBX), followed by fields separated by the pipe character |. Fields are numbered by position — MSH.9 is the 9th field and contains the message type. Fields can contain sub-components separated by carets (^) and repetitions separated by tildes (~).

A complete HL7 v2.x message is a sequence of these segments, where each segment carries a specific category of clinical or administrative information. The MSH (Message Header) always comes first and establishes the message type, version, and routing information. Patient demographics live in PID. Visit information is in PV1. Observation results appear in OBX.

The Most Important Segments

While the HL7 v2.x specification defines hundreds of segment types, a handful appear in nearly every integration scenario:

MSH — Always the first segment. Contains message type (MSH.9), control ID for deduplication (MSH.10), sending and receiving application/facility, and HL7 version.
PID — The core patient identifier segment. PID.3 contains the patient identifier list (MRN, national ID), PID.5 the patient name, and PID.7 the date of birth.
PV1 — Patient visit details: patient class (inpatient/outpatient), assigned location, attending doctor, and admission type. Critical for ADT workflows.
OBR — The order request segment in ORM and ORU messages. OBR.4 contains the universal service identifier (test code) and is the key field for mapping lab orders to your test catalog.
OBX — Individual observation or result in an ORU message. OBX.2 declares the value type (NM for numeric, ST for string, CWE for coded), OBX.3 the observation identifier, and OBX.5 the actual value.
EVN — Event type metadata for ADT messages. Contains the event type code (EVN.1) that distinguishes A01 (admit), A03 (discharge), A08 (update), and other patient movement events.

HL7 Data Types

Like DICOM's Value Representations, HL7 defines data types that govern how field values are encoded. Key data types include:

ST (String) — Plain text up to a defined max length. Used for free-text fields like notes and descriptions.
TS (Timestamp) — Date/time string in YYYYMMDDHHMMSS format. HL7 allows partial precision (YYYYMMDD for dates only).
CX (Extended Composite ID) — A structured identifier with assigning authority and identifier type code. Used for MRNs, account numbers, and national patient IDs.
XPN (Extended Person Name) — Structured name with family name, given name, middle initial, suffix, prefix, and name type code separated by carets.
CE/CWE (Coded Element / Coded with Exceptions) — A coded value with identifier, description, and coding system (ICD-10, LOINC, SNOMED). The standard way to transmit coded clinical data.
NM (Numeric) — Decimal number as a string. Used for test results, quantities, and measurements.
HD (Hierarchic Designator) — An application or facility identifier. Used in MSH.3/4/5/6 for message routing.

Message Type Structure

HL7 v2.x defines message types as combinations of a message code and event code, written as Code^Event. For example: ADT^A01 (Admit), ORM^O01 (Order), ORU^R01 (Result), SIU^S12 (New Appointment), and MDM^T02 (Document). Each message type has a defined segment grammar specifying which segments are required, which are optional, and in what order they appear. The Message Types tab in this browser shows these grammars for the 10 most common message types.

Practical Use Cases for This Browser

Interface analysts and integration engineers use this segment browser in several everyday scenarios:

Writing interface specifications: Reference field positions and data types when documenting mapping logic from source system fields to destination system fields.
Debugging missing or misplaced data: When a receiving system reports a missing value, look up the segment to confirm the expected field position and data type.
Understanding a new message type: Browse the ADT^A31 or DFT^P03 schema to understand what segments to expect when building a new interface.
Training new analysts: The combination of segment definitions and message schemas makes a self-contained HL7 v2.x primer for team onboarding.

Frequently Asked Questions

Does this tool support all HL7 v2.x versions?

The segment definitions are based on HL7 v2.5 and v2.7, which cover the vast majority of production HL7 interfaces in use today. Minor version differences may have slightly different field lists or cardinality rules, but the core segment structure is consistent across HL7 v2.3 through v2.8.

Does this tool parse or process actual HL7 messages?

No. This browser is a pure reference tool containing only public HL7 standard segment definitions. No HL7 message files are uploaded, no patient data is processed, and no PHI is involved. To parse actual HL7 messages, use the HL7 Viewer tool.

How many segments does this browser cover?

The browser includes 21 common HL7 v2.x segments covering all segments used in the 10 message type schemas: MSH, PID, PV1, OBX, OBR, NK1, EVN, ORC, NTE, MSA, AL1, DG1, IN1, GT1, PV2, SCH, TXA, FT1, AIG, AIL, and AIP.

What are the 10 message types included?

ADT^A01 (Admit), ADT^A04 (Register Outpatient), ADT^A08 (Update Patient), ADT^A31 (Update Person), ORM^O01 (Order), ORU^R01 (Observation Result), SIU^S12 (New Appointment), MDM^T02 (Document Status Change), BAR^P01 (Add Patient Account), and DFT^P03 (Post Financial Transaction).

What does 'Required' mean for a field vs. a segment?

At the segment level, Required means the segment must appear in messages of that type — its absence makes the message non-conformant. At the field level, Required means the field value must be populated when the segment is sent. Fields marked Repeating can appear multiple times within a single segment, separated by the tilde (~) delimiter.

What HL7 data types appear most often?

The most common data types are CX (Extended Composite ID) for identifiers like MRNs, XPN (Extended Person Name) for patient and provider names, TS (Timestamp) for dates and times, CE/CWE (Coded Element) for clinical codes like ICD and LOINC, and ST (String) for free-text content.

Can I use this to validate my HL7 interface?

You can use it as a reference to manually check field mappings and segment composition. For automated validation against schemas, use the HL7 Viewer which includes segment parsing and required-field checking against actual message content.

What is the difference between a segment and a field in HL7?

A segment is a named group of related data elements (e.g., PID for patient demographics). A field is an individual data item within that segment, identified by its position number — for example, PID.5 is the Patient Name field within the Patient Identification segment.

Are Z-segments (custom segments) included?

No. This browser contains only standard HL7 segment definitions. Z-segments are custom extensions defined by individual healthcare organizations or vendors and are not part of the public standard. Check your specific vendor's documentation for local Z-segment definitions.

Can I export the segment definitions?

Yes. Use the Export CSV button on the Segments tab to download the currently visible segment list with descriptions and field counts. You can filter first by data type or search query to export only the segments relevant to your project.

Sources

Reviewed by Healthcare IT Editorial Team — Clinical Informatics Specialists

Last reviewed: 2026-04-09

hl7-tools 2026-04-09

HL7 v2.x Segment Field Reference: A Complete Guide for Integration Engineers

Complete HL7 v2.x segment field reference covering all standard segments, field positions, data types, and optionality rules for healthcare integration.

Learn more