Segment Reference

EDI transactions are built from segments — single lines of data that each serve a specific purpose. Understanding segment structure is essential for reading and troubleshooting EDI files.

What Are Segments?

A segment is a single line in an EDI file, starting with a 2-3 character segment ID and ending with a segment terminator (usually ~). Each segment represents a specific type of information.

Basic Structure

NM1*IL*1*SMITH*JOHN*A***MI*ABC123456~
│    │  │   │     │   │ │ │  │        │
│    └──┴───┴─────┴───┴─┴─┴──┴────────┴── Elements (separated by *)
└── Segment ID                         └── Segment Terminator

Key Concepts

Term	Definition
Segment ID	2-3 character identifier (e.g., `NM1`, `CLM`, `SVC`)
Element	Individual data field within a segment
Element Separator	Character separating elements (usually `*`)
Composite	Element containing sub-elements (separated by `:`)
Segment Terminator	Character ending the segment (usually `~`)
Required Element	Must be present for the segment to be valid
Situational Element	Required only in certain circumstances

Understanding Elements

Elements are numbered starting from 01 after the segment ID. Empty elements still need their separators:

DMG*D8*19800515*M**~
    │    │       │  ││
    01   02      03 0405 (empty)

DMG01: D8 — Date format qualifier
DMG02: 19800515 — Date of birth
DMG03: M — Gender
DMG04: Empty
DMG05: Empty (trailing empties can be omitted)

How EDI Paisan Displays Elements

In the segment detail panel, EDI Paisan shows:

DMG - Demographic Information
├── DMG01: D8 (Date Format: CCYYMMDD)
├── DMG02: 19800515 (Date of Birth)
├── DMG03: M (Gender: Male)

Each element is labeled with its position and meaning based on the transaction type context.

Composite Elements

Some elements contain sub-elements separated by colons (:). These are called composite elements.

Example: Healthcare Service Code

SV1*HC:99213:25*125*UN*1~
     │   │    │
     │   │    └── Modifier
     │   └── CPT Code
     └── Code Type (HC = HCPCS)

This SV1-01 composite contains:

SV1-01-1: HC — Procedure code qualifier
SV1-01-2: 99213 — CPT/HCPCS code
SV1-01-3: 25 — Modifier

Common Composite Patterns

Element	Components	Example
Procedure Code	Type:Code:Mod1:Mod2:Mod3:Mod4	`HC:99213:25`
Diagnosis Code	Type:Code	`ABK:J0690`
Amount	Qualifier:Amount	`B6:1500.00`
Provider ID	Type:ID	`XX:1234567890`

Envelope Segments

Every EDI file is wrapped in envelope segments that identify the transmission:

ISA — Interchange Control Header

The ISA segment starts every EDI file and has fixed-length elements:

ISA*00*          *00*          *ZZ*SENDER         *ZZ*RECEIVER       *240115*1200*^*00501*000000001*0*P*:~

Element	Length	Description
ISA01	2	Authorization Info Qualifier
ISA02	10	Authorization Information
ISA03	2	Security Info Qualifier
ISA04	10	Security Information
ISA05	2	Interchange Sender ID Qualifier
ISA06	15	Interchange Sender ID
ISA07	2	Interchange Receiver ID Qualifier
ISA08	15	Interchange Receiver ID
ISA09	6	Interchange Date (YYMMDD)
ISA10	4	Interchange Time (HHMM)
ISA11	1	Repetition Separator
ISA12	5	Interchange Control Version
ISA13	9	Interchange Control Number
ISA14	1	Acknowledgment Requested
ISA15	1	Usage Indicator (P=Production, T=Test)
ISA16	1	Component Element Separator

ISA Fixed-Width

Unlike other segments, ISA elements have fixed widths. That's why you see padding spaces. EDI Paisan handles this automatically.

IEA — Interchange Control Trailer

Closes the interchange:

IEA*1*000000001~

IEA01: Number of included functional groups
IEA02: Interchange control number (must match ISA13)

GS — Functional Group Header

Groups related transactions:

GS*HC*SENDER*RECEIVER*20240115*1200*1*X*005010X222A1~

Element	Description
GS01	Functional ID Code (`HC`=Healthcare Claim)
GS02	Application Sender's Code
GS03	Application Receiver's Code
GS04	Date (CCYYMMDD)
GS05	Time (HHMM)
GS06	Group Control Number
GS07	Responsible Agency Code (`X`=X12)
GS08	Implementation Version

GE — Functional Group Trailer

GE*1*1~

GE01: Number of transaction sets in group
GE02: Group control number (must match GS06)

ST — Transaction Set Header

Starts each transaction:

ST*837*0001*005010X222A1~

ST01: Transaction Set ID (837, 835, 270, 271)
ST02: Transaction Set Control Number
ST03: Implementation Convention Reference

SE — Transaction Set Trailer

SE*42*0001~

SE01: Number of segments in transaction (including ST and SE)
SE02: Transaction Set Control Number (must match ST02)

Key Segments by Transaction Type

837 — Claims

Segment	Name	Purpose	Loop
BHT	Beginning of Hierarchical Transaction	Transaction info, purpose	Header
HL	Hierarchical Level	Establishes parent-child structure	2000*
NM1	Individual or Organizational Name	Identifies entities	2010*
N3	Address Information	Street address	2010*
N4	Geographic Location	City, state, ZIP	2010*
REF	Reference Identification	IDs, account numbers	Various
DMG	Demographic Information	DOB, gender	2010*
CLM	Claim Information	Claim details, charges	2300
DTP	Date/Time Reference	Service dates, admission	Various
HI	Health Care Information Codes	Diagnosis codes	2300
SBR	Subscriber Information	Coverage details	2000B
SV1	Professional Service	Line item (837P)	2400
SV2	Institutional Service	Line item (837I)	2400
LX	Transaction Set Line Number	Line counter	2400

CLM — Claim Information

The heart of an 837 transaction:

CLM*PATIENT-ACCT-123*500***11:B:1*Y*A*Y*Y~

Element	Description
CLM01	Patient Account Number
CLM02	Total Claim Charge Amount
CLM03	Not used
CLM04	Not used
CLM05	Place of Service:Facility Code:Frequency Code
CLM06	Provider Signature on File (Y/N)
CLM07	Assignment or Plan Participation Code
CLM08	Benefits Assignment Certification
CLM09	Release of Information Code

SV1 — Professional Service (837P)

SV1*HC:99213:25*125*UN*1***1:2:3~

Element	Description
SV101	Composite - Procedure Code (HC:CPT:Modifiers)
SV102	Line Item Charge Amount
SV103	Unit Basis (UN=Unit)
SV104	Service Unit Count
SV105	Place of Service
SV106	Not used
SV107	Composite - Diagnosis Code Pointers

HI — Health Care Information Codes (Diagnosis)

HI*ABK:J0690*ABF:E119*ABF:I10~

Qualifier	Description
ABK	ICD-10 Principal Diagnosis
ABF	ICD-10 Diagnosis
BK	ICD-9 Principal Diagnosis
BF	ICD-9 Diagnosis

835 — Remittance

Segment	Name	Purpose	Loop
BPR	Financial Information	Payment method, amount	Header
TRN	Reassociation Trace Number	Check/EFT number	Header
DTM	Date/Time Reference	Production date	Header
N1	Name	Payer/Payee identification	1000*
LX	Transaction Set Line Number	Header grouping	2000
CLP	Claim Level Payment	Claim adjudication	2100
CAS	Claim Adjustment Segment	Adjustments, denials	2100/2110
NM1	Individual or Organizational Name	Patient, provider	2100
SVC	Service Payment Information	Line-level payment	2110
AMT	Monetary Amount	Various amounts	2100/2110
PLB	Provider Level Balance	Provider adjustments	Trailer

BPR — Financial Information

BPR*I*1500.00*C*ACH*CTX*01*999999999*DA*1234567890**01*999999999*DA*9876543210*20240120~

Element	Description
BPR01	Transaction Handling Code (I=Remittance Info Only, C=Payment)
BPR02	Total Actual Provider Payment Amount
BPR03	Credit/Debit Flag
BPR04	Payment Method (ACH, CHK, NON)
BPR16	Check Issue/EFT Date

CLP — Claim Payment

CLP*PATIENT123*1*500.00*400.00*50.00*MA*CLAIM123*11~

Element	Description
CLP01	Patient's Claim Number
CLP02	Claim Status Code
CLP03	Total Claim Charge Amount
CLP04	Total Claim Payment Amount
CLP05	Patient Responsibility Amount
CLP06	Claim Filing Indicator Code
CLP07	Payer's Claim Control Number
CLP08	Facility Code Value

Claim Status Codes (CLP02):

Code	Meaning
1	Processed as Primary
2	Processed as Secondary
3	Processed as Tertiary
4	Denied
19	Processed as Primary, Forwarded
20	Processed as Secondary, Forwarded
22	Reversal of Previous Payment

CAS — Claim Adjustment Segment

CAS*CO*45*100.00**42*50.00~

Element	Description
CAS01	Claim Adjustment Group Code
CAS02	Adjustment Reason Code
CAS03	Adjustment Amount
CAS04	Adjustment Quantity
(Repeats)	Up to 6 adjustments per CAS segment

Adjustment Group Codes (CAS01):

Code	Meaning	Patient Responsibility?
CO	Contractual Obligation	No — write-off
CR	Corrections and Reversals	Varies
OA	Other Adjustments	Varies
PI	Payer Initiated Reduction	No
PR	Patient Responsibility	Yes

270 — Eligibility Inquiry

Segment	Name	Purpose	Loop
BHT	Beginning of Hierarchical Transaction	Transaction purpose	Header
HL	Hierarchical Level	Structure	2000*
NM1	Individual or Organizational Name	Entity identification	2100*
REF	Reference Identification	IDs, group numbers	2100*
DMG	Demographic Information	DOB, gender	2100C
DTP	Date/Time Reference	Date of service	2100C
EQ	Eligibility or Benefit Inquiry	What's being asked	2100C

EQ — Eligibility Inquiry

EQ*30~

EQ01: Service Type Code (see Qualifier Codes for full list)
EQ02: Composite Medical Procedure (optional)

Common Service Type Codes:

Code	Description
30	Health Benefit Plan Coverage
1	Medical Care
33	Chiropractic
47	Hospital
86	Emergency Services

271 — Eligibility Response

Segment	Name	Purpose	Loop
BHT	Beginning of Hierarchical Transaction	Transaction info	Header
HL	Hierarchical Level	Structure	2000*
NM1	Individual or Organizational Name	Entities	2100*
REF	Reference Identification	IDs	2100*
EB	Eligibility or Benefit Information	Coverage details	2110*
HSD	Health Care Services Delivery	Quantity limits	2110*
DTP	Date/Time Reference	Effective dates	2110*
MSG	Message Text	Free-form notes	2110*

EB — Eligibility/Benefit Information

The key segment in 271 responses:

EB*1*IND*30*HM*GOLD PLAN~

Element	Description
EB01	Eligibility/Benefit Information Code
EB02	Coverage Level Code (IND, FAM, etc.)
EB03	Service Type Code
EB04	Insurance Type Code
EB05	Plan Coverage Description
EB06	Time Period Qualifier
EB07	Monetary Amount
EB08	Percent

EB01 Information Codes:

Code	Meaning
1	Active Coverage
6	Inactive
I	Non-Covered
A	Co-Insurance
B	Co-Payment
C	Deductible
F	Limitations
G	Out of Pocket Maximum
R	Other or Additional Payor

Name Segments (NM1)

The NM1 segment identifies entities and appears throughout EDI transactions:

NM1*IL*1*SMITH*JOHN*A***MI*ABC123456~

Element	Description
NM101	Entity Identifier Code (who this is)
NM102	Entity Type Qualifier (1=Person, 2=Organization)
NM103	Last Name or Organization Name
NM104	First Name (persons only)
NM105	Middle Name (persons only)
NM106	Name Prefix
NM107	Name Suffix
NM108	Identification Code Qualifier
NM109	Identification Code

See Qualifier Codes for complete lists of entity identifiers and ID qualifiers.

Address Segments (N3/N4)

Addresses are split across two segments:

N3 — Street Address

N3*123 MAIN STREET*SUITE 100~

N301: Address Line 1
N302: Address Line 2

N4 — Geographic Location

N4*ANYTOWN*SC*29601*US~

N401: City Name
N402: State/Province Code
N403: Postal Code
N404: Country Code

Date Segments (DTP)

Date/time information uses consistent qualifiers:

DTP*472*D8*20240115~

Element	Description
DTP01	Date/Time Qualifier
DTP02	Date/Time Format (D8=Date, RD8=Date Range)
DTP03	Date/Time Value

Common Date Qualifiers (DTP01)

Code	Description
096	Discharge Date
232	Claim Statement Period Start
233	Claim Statement Period End
291	Plan Begin
292	Plan End
304	Latest Visit/Consultation
314	Disability Begin
360	Initial Treatment
435	Admission
472	Service
573	Date Claim Paid

Date Formats (DTP02)

Code	Format	Example
D8	CCYYMMDD	20240115
RD8	CCYYMMDD-CCYYMMDD	20240115-20240131

Reading Segments in EDI Paisan

Using the Tree View

Expand loops to see contained segments
Click a segment to see element breakdown
Element tooltips show qualifier meanings

Using Search

Search by segment ID to find all occurrences:

NM1 — Find all name segments
CAS — Find all adjustments
EB*1 — Find active coverage responses

Segment Colors

EDI Paisan color-codes segments by category:

Color	Category	Examples
Blue	Identification	NM1, N1, REF
Green	Financial	CLM, SVC, CLP, AMT
Orange	Dates	DTP, DTM
Purple	Codes	HI, SV1, EB
Gray	Envelope	ISA, GS, ST, SE

Common Issues

Missing Required Elements

If a required element is missing:

NM1*IL*1*SMITH****MI*~   ← Missing first name (NM104)

EDI Paisan will show a validation warning.

Invalid Qualifier Codes

Unrecognized qualifiers display with a warning badge. Check Qualifier Codes for valid values.

Trailing Delimiters

Extra delimiters at segment end are allowed but unnecessary:

DTP*472*D8*20240115~     ← Clean
DTP*472*D8*20240115***~  ← Works but wasteful

Loop Hierarchy — How segments organize into loops
Qualifier Codes — Complete code lookup tables
837P Professional Claims — 837P segment details
835 Remittance — 835 segment details
Viewing Files — Using the EDI Paisan viewer

Segment Reference ​

What Are Segments? ​

Basic Structure ​

Key Concepts ​

Understanding Elements ​

How EDI Paisan Displays Elements ​

Composite Elements ​

Example: Healthcare Service Code ​

Common Composite Patterns ​

Envelope Segments ​

ISA — Interchange Control Header ​

IEA — Interchange Control Trailer ​

GS — Functional Group Header ​

GE — Functional Group Trailer ​

ST — Transaction Set Header ​

SE — Transaction Set Trailer ​

Key Segments by Transaction Type ​

837 — Claims ​

CLM — Claim Information ​

SV1 — Professional Service (837P) ​

HI — Health Care Information Codes (Diagnosis) ​

835 — Remittance ​

BPR — Financial Information ​

CLP — Claim Payment ​

CAS — Claim Adjustment Segment ​

270 — Eligibility Inquiry ​

EQ — Eligibility Inquiry ​

271 — Eligibility Response ​

EB — Eligibility/Benefit Information ​

Name Segments (NM1) ​

Address Segments (N3/N4) ​

N3 — Street Address ​

N4 — Geographic Location ​

Date Segments (DTP) ​

Common Date Qualifiers (DTP01) ​

Date Formats (DTP02) ​

Reading Segments in EDI Paisan ​

Using the Tree View ​

Using Search ​

Segment Colors ​

Common Issues ​

Missing Required Elements ​

Invalid Qualifier Codes ​

Trailing Delimiters ​

Related Documentation ​