COMMAND CODES

• CC SFDISP to check CC's that are assigned to your profile
• ENMOD - displays the most current entity information for a TP
  • including pending charges, notices, and letters sent
• INOLES - Master file entity info/valid name checks with social security/cross reference spouse info
  • can be used for disclosure purposes.
• TRDBV - researches filed returns; both electronic and paper.
  • will show both accepted and rejected returns.
  • only lines TP filled out are reflected.
  • when the tax period is not used it will list every return currently accessible.
• RTVUE - displays original 1040 info that shows every line
  • will list all math errors reflected vs TXMOD only reflecting one at a time
• TXMODA - all tax module information for a specific tax period on the TIF.
  • stores the TIN, File Source, TIN Type, MFT, Tax Period, Case Control Indicator, Name Control and, for EPMF, Plan Number as required data elements for subsequent processing.
• DDBCK - used for validating additional children and credits claimed on amended returns.
  • displays the dependents & qualifying children from the original posted return or as last modified.
  • by entering update request into DDBCK, a user can then modify the data to reflect changes from the submitted 1040X.
• IRPTR- wage, income, and investment information
• NAMES: used to search the national file for a TP's return not located under their TIN.
• INOLE: displays the entity information as compared to the SSA or IRS Master File.
• IMFOLE: displays the posted entity information.
• CFINK: searches the CAF for the entity information on the taxpayer's authorized representative.
• ESTAB: requests a paper processed return from files.
• FFINQ: shows when the return has been input and the current status of the return.
  • used especially when disclosing a first-time filer.

ASED/RSED/CSED/ERSED

Statute Cases

21.5.2.4.23.4 Statute Imminent Documents 25.6.1.5 Basic Guide for Processing Cases with Statute of Limitations Issues 25.6.1.7.2 Time When Payments and Credits are Considered to be Made 25.6.1.10.2.7.2.2 Two-year Rule 25.6.1.10.2.9 Claims for Credit or Refund- Taxpayers in Special Situations 21.5.3.4.3 Tax Decrease and Statute Consideration TCD 0071-Statute of Limitations Overview TCD 0072 Assessment Statute Expiration Date (ASED) TCD 0073 Collection Statute Expiration Date (CSED) TCD 0074 Refund Statute Expiration Date (RSED)

Statute searching a case:

• See if the case in question is a statute year

• Look at the ASED (if more than 90 days out, no need to continue. If 90 days or less continue!)

• Determine how much tax is currently on the account

• Take the TC150 amount and add/subtract and amounts from any adjustments i.e. TC's 29X/30X/40X

• Look at the taxpayer's claim and determine whether they are making any changes to their total tax

• Line 11, column C on the Form 1040X

• If the number is increasing send the claim to Statutes

• Look at the taxpayer's claim and determine if they are making any changes to their credits

Complete Study Guide: IRS Command Codes DDBCK, DDBCV & DDBCS

• Dependent's Database Check (DDBCK) used to update dependent credits for current tax year and 2 yars prior. [The IRS uses a computer system called the Dependent Database (DDB) to check whether taxpayers are claiming certain children and tax credits correctly.]
• before using, always use INOLES to veryfiy TIN/name/DOB
• used for validating additional children and credits claimed on amended returns (1040X)
• ‘*’ means : invalid name control, 'x' in the credit field indicates that it was disallowed when the return was filed.
• PRIM: Primary Taxpayer, SECD: Secondary Taxpayer / Spouse, CH1 to CH6: Children or Dependents 1 through 6
• SSN/RETRN:The Social Security Number or ITIN reported on the original return, SSN/AMEND:The SSN or ITIN added, changed, or reported on the amended return (Form 1040-X), N/C (Name Control):The 4-letter IRS Name Control code (usually the first 4 letters of the individual's last name) used for IRS/SSA matching, BIRTH DT:Date of Birth of the individual in YYYYMMDD format (retrieved from Social Security Administration records), DEATH DT:Date of Death in YYYYMMDD format (if applicable according to SSA records).
• EIC: Earned Income Tax Credit, EX/DP: Exemption / Dependent Status, CTC: Child Tax Credit, CCC: Child and Dependent Care Credit, EDCR: Educator Expense Deduction / Credit, ADPT: Adoption Credit
• Single-letter status indicators (such as Y for Yes/Claimed, A for Add, D for Delete, or CR for Credit), X for CLAIM AMOUNT (previous)
• DLN: Document Locator Number of the tax return. ORIG RTN: Date the original return was posted/processed (YYYYMMDD). CL-RCVDDT: Date the amended return or claim was received by the IRS (YYYYMMDD). FS: Filing Status on the original return. FS/AMEND: Filing Status as requested on the amended return.
• RefCR ACTC (Refundable Credit - Additional Child Tax Credit): Tracks changes or increases/decreases specific to the refundable portion of the Child Tax Credit, RefCR AOTC (Refundable Credit - American Opportunity Tax Credit): Tracks adjustments made to education-related refundable credits like the AOTC

  DDBCK nnn-nn-nnnn 30YYYYMM
    
  DLN:20261234567890  ORIG RTN:20260412  CL-RCVDDT:20260920  FS:1  FS/AMEND:1
        SSN/RETRN SSN/AMEND  N/C   BIRTH DT DEATH DT EIC EX/DP CTC  CCC  EDCR ADPT
  PRIM  123456789            ABCD  YYYYMMDD YYYYMMDD         Y             Y    CR
  SECD  123456789 123456789  ABCD  YYYYMMDD YYYYMMDD         Y             Y
  CH1   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   Y     Y    Y    Y    Y    Y
  CH2   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   A     A    A        
  CH3   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   
  CH4   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   
  CH5   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   
  CH6   123456789 123456789  ABCD  YYYYMMDD YYYYMMDD   

  CATEGORY CODE: EICA        CLAIM AMOUNT: 1234         SCHED-C: Y
 
CLAIM RECEIVED DATE:
NEW: 20260920       ADD

PREVIOUS CLAIMS:
     20260805  EICX   EDIT  DELETE
     20260710  EICX
     20260601  EICN

MESSAGES:
NO OPEN AIMS INDICATED IN THIS EXAMPLE           DDBCK RETURN SUMMARY

-------------------------------------------------------------
 after adding following type (After TRANSMIT, the system validates the changes.)
 -------------------------------------------------------------
CATEGORY: EICX    CLAIM AMOUNT: 02250       SCHEDULE C INDICATOR: N

             ORIGINAL      INCREASE/DECREASE
AGI           028000             -01000
EIC           003000             +01500
RefCR ACTC    XXXXX         
RefCR AOTC    XXXXX
                              TRANSMIT



----------------------------------------------------------------
DDBCK — Schedule C Update Screen
----------------------------------------------------------------
DDBCK 987-65-4321 30202512

        DDBCK RETURN UPDATE - SCHEDULE C

                                  ORIGINAL   CORRECTED

AGI ORIGINAL:       037000
AGI INC/DEC:        +02500

SCHEDULE C:

GROSS RECEIPTS                    050000     055000
COST OF GOODS SOLD                010000     012000
HOME OFFICE EXPENSE               003000     003500
NET PROFIT                        037000     039500


EIC ORIGINAL:       01500

WAGES ORIGINAL:     12000
WAGES INC/DEC:      00000


                              TRANSMIT

It displays the original taxpayer and dependent information, credit indicators, and previous claims. Y means a credit was claimed on the original return; a blank indicates no use. The employee can select ADD, EDIT, DELETE, or view a previous claim by selecting its date and pressing TRANSMIT.

DDBCK 123-45-6789 30202512

DLN: 20261234567890  RTN DT: 20260412
LAST CLAIM: 20260805     FS: 1   AMEND FS: 1

     SSN/RETURN SSN/AMEND  N/C   DOB      DOD   EIC DEPD CTC CCC EDCR ADPT

PRIM 123456789             SMIT  19800512   -     Y     -   -   -    -
SECD                      ----
CH1  234567890             SMIT  20160615   Y    Y    Y   -   -    -
CH2
                           -    -    -   -   -    -
CH3
CH4
CH5
CH6

CLAIM RECEIVED DATE:
NEW: 20260920       ADD

PREVIOUS CLAIMS:
     20260805  EICX   EDIT  DELETE
     20260710  EICX
     20260601  EICN

MESSAGES:
NO OPEN AIMS INDICATED IN THIS EXAMPLE

                   DDBCK RETURN SUMMARY

Based on IRS Internal Revenue Manual (IRM) 2.4.58 — all 23 pages, revised March 31, 2025.

This guide explains the manual in simple English while keeping the important technical details, procedures, screen fields, validation results, and error messages. It's designed so you can study, revise, and understand the entire topic without having to keep reopening the original PDF.

1. The big picture — what is this manual about?

The IRS uses a computer system called the Dependent Database (DDB) to check whether taxpayers are claiming certain children and tax credits correctly.

For example, someone may file an original tax return and later submit Form 1040-X (an amended return) to claim another child or an additional tax credit.

The IRS needs to check whether that new claim is valid, duplicates another claim, or needs examination.

This is where the three command codes come in.

Command code	Main job	Easy way to remember
DDBCK	Checks claims, validates changes, updates records, and determines what action is needed	Check + Update
DDBCV	Allows employees to view and research validation information without saving changes or sending cases to examination	Check + View
DDBCS	Helps headquarters control case-selection work plans and capacity	Selection Setup

Example

A taxpayer originally claimed one child for the Earned Income Tax Credit (EITC).

Later, they submit Form 1040-X to add a second child.

Using DDBCK, an authorized IRS employee can:

1. Retrieve the original return information.
2. Add the second child's information.
3. Identify the additional credit being claimed.
4. Check the child's SSN, name, age, and other eligibility-related information.
5. Check for duplicate use of the child's TIN and applicable DDB rules.
6. Read the result to determine whether to process the adjustment, refer the case to examination, or send it to classification.

The most important concept: DDBCK helps determine whether an additional claim can proceed through normal processing or must receive further review.

---

2. Why does the IRS use DDBCK?

DDBCK is primarily used for additional claims involving children and credits from:

• Amended individual income tax returns (Form 1040-X).
• Math error notices and related adjustments.
• Certain taxpayer correspondence and telephone-related claims.

The credits discussed in the manual include:

Credit	What it generally means
EITC / EIC	Earned Income Tax Credit
CTC	Child Tax Credit
CCC	Child Care Credit
EDCR	Education Credit
ADPT CR	Adoption Credit
Exemption / DEPD	Exemption or dependent claim

The DDB is a rules-based selection application designed to identify questionable claims, particularly refundable-credit claims.

Where does the information come from?

Source	What it provides
IRTF / RTVUE	Information from filed tax returns
DM1 / INOLE	Taxpayer identification and related entity information
IMF / IMFOL	Individual taxpayer account information
DUPTIN / DUPOL	Information used to detect and record duplicate TIN use

Remember: DDBCK does not simply accept the amended return as correct. It compares the new information against existing records and validation rules.

3. Who can use these command codes?

Code	Who can access or use it
DDBCK	Restricted to Accounts Management, Examination, and Submission Processing
DDBCV	Available to all IRS functions for viewing and research
DDBCS	Used by headquarters for selection and workload planning

The manual identifies Taxpayer Services (TS) as both policy owner and program owner.

Taxpayer Services Return Integrity and Compliance Services (RICS) business partners provide system design, program requirements, and documentation. Applications Development handles operations and maintenance.

The main IRS audiences and stakeholders include TS, Small Business/Self-Employed (SB/SE), Large Business and International (LB&I), Tax Exempt and Government Entities (TE/GE), and Submission Processing (SP).

---

4. Important abbreviations you must know

Abbreviation	Full meaning / purpose
CC	Command Code
DDB	Dependents Data Base
IDRS	Integrated Data Retrieval System
AIMS	Audit Information Management System
IMF	Individual Master File
EITC / EIC	Earned Income Tax Credit
SSN	Social Security Number
TIN	Taxpayer Identification Number
AMS	Account Management Services
TS	Taxpayer Services
SB/SE	Small Business Self-Employed
SP	Submission Processing
RICS	Return Integrity and Compliance Services
1040X	Amended individual income tax return
QC	Qualifying Child
NC	Name Control
AGI	Adjusted Gross Income
DLN	Document Locator Number
MFT	Master File Tax code
TC	Transaction Code

The manual also uses the terms ADJ54, CAT A, BS 74, FCR, OR/AR, and several internal result codes without fully defining all of them. This guide preserves those codes rather than guessing at their meanings.

---

5. The complete DDBCK workflow

1. Enter DDBCK and the primary TIN. Retrieve the original return or latest modified claim information.
2. Read the Return Summary Screen. Review dependents, credits, prior claims, filing status, and account warnings.
3. Add or edit the amended claim. Enter children, credit changes, filing status, claim amount, and Schedule C indicator.
4. Run validation. Check identification, age, duplicate claims, and applicable DDB rules.
5. Review the Validation Result Screen. Read the decision on Page 1 and detailed rule results on Page 2.
6. Follow the displayed result: normal processing (if permitted), examination (if selected), or classification (if required).

This is the fundamental sequence to remember throughout the rest of the guide.

---

6. How to start DDBCK or DDBCV

Required input

The main required information is:

Field	What to enter
Command code	DDBCK or DDBCV
Definer	Blank
Primary TIN	Edited format: nnn-nn-nnnn
MFT	The applicable MFT; the manual specifies 30
Tax period	Six numeric digits, YYYYMM

The request-screen layout in Exhibit 2.4.58-1 places the information as follows:

Line	Position	Field
1	01–05	Command code
1	07–17	Primary edited SSN
1	18	Validity digit: blank or *
1	19–26	MFT and tax period

An illustrative edited SSN format is 123-45-6789. It is only a format example, not a real taxpayer record.

When the request is transmitted, the system searches for the posted return and displays the dependents and qualifying children from the original return or most recent stored modification.

If no posted return can be located, it displays an error. If the SSN is secondary or has been merged, the system may identify another SSN that needs to be researched.

7. Return Summary Screen — understand everything displayed

The Return Summary Screen is where the employee reviews the account before making changes.

A. General tax return information

The screen provides:

Field	Meaning
DLN	Document Locator Number of the posted return
Return settlement date	Date associated with the original return processing
Last claim date	Latest claim received date recorded in DDBCK
Original filing status	Filing status on the originally filed return
Updated filing status	Filing status after a recorded amendment
Primary taxpayer SSN	SSN of the main taxpayer
Secondary taxpayer SSN	Spouse's SSN, where applicable
Name Control	Name-control information used for identification validation
DOB	Date of birth
DOD	Date of death
Credit indicators	Which credit each individual was claimed for

The screen can display the primary taxpayer, secondary taxpayer, and up to six children.

B. The four main credit indicators

These are especially important to memorize.

Indicator	Meaning	Explanation
Y	Originally claimed	The credit was claimed on the original return.
A	Added	The credit was subsequently added on an amended return.
D	Deleted	The credit was removed through an amendment.
x	Disallowed	The credit was disallowed when the return was filed.
Blank	Not used	Credit was not used for the person.

Other important identification messages:

• INVLD SSN — the SSN from the original return was invalid.
• * next to the Name Control — the original name control was invalid.

Example

Suppose a child's credit indicators show:

EIC	DEPD	CTC	CCC	EDCR
Y	Y	A	blank	blank

This means the child was originally claimed for EIC and as a dependent, while the Child Tax Credit was added later. No use is indicated for child care or education credits.

Important: An indicator records how the credit was claimed or changed. It does not independently prove eligibility.

C. Important account warning messages

The bottom part of the screen can display warnings that require attention under the applicable IRM procedures.

Message or condition	Why it matters
Open AIMS	There is open examination-related information
Math error	A math error issue exists
O freeze	Account has this freeze condition
Recertification indicator	EITC recertification-related information requires review
IMFOL entity data not found	Entity information was not found
IMFOL tax module data not found	Tax-module data was not found
Combat zone case	Special procedures apply
Prior-year / possible statute	Time-limit issues may require review
Possible RECON case	Follow the applicable IRM
Other freeze codes	Follow the applicable freeze-code instructions
Form 8862	The received date may need to be entered when working from this form

These warnings are not all automatic rejections. Their importance is that the employee must recognize the condition and follow the related IRS procedures.

D. The STOP condition

Sometimes the claim date entry field is disabled and replaced with:

**STOP**

The manual identifies these triggers:

• An L freeze on the module.
• Transaction Code TC290 on the module.
• A 2-year or 10-year EITC ban.
• An old tax period.

When STOP appears, normal DDBCK input is disabled. Do not treat this as a normal add-request screen.

---

8. Adding, viewing, editing, or deleting a claim

The Summary Screen provides point-and-shoot fields. The system performs different actions depending on where the cursor is positioned when TRANSMIT is pressed.

Action	How it works
ADD	Enter a new claim received date, place the cursor on ADD, and transmit
VIEW	Place the cursor on a previous claim's received date and transmit
EDIT	Place the cursor on EDIT for the latest record and transmit
DELETE	Place the cursor on DELETE for the latest record and transmit

Important rules

New claims: The system may automatically populate the claim received date using the latest amended return date. Otherwise, YYYYMMDD appears, and the user must enter the date.

Previous claims: Up to four prior claims are shown, with the latest first. The claim received date and category code appear for each.

Editing: If the change belongs to a previously entered claim, use EDIT instead of incorrectly adding a separate claim.

Deleting: Only the most recent record can be changed or deleted. Older records are available for viewing.

Examination restriction: After an examination-selected record has passed the specified time and TC424 has been sent, it cannot be modified or deleted as described in the error-message section.

Example: If a claim was already entered with an incorrect child SSN, the employee should use the appropriate EDIT function rather than creating a second claim for the same adjustment.

---

9. Return Update Screen — how information is changed

The Return Update Screen opens when the user selects ADD or EDIT from the Summary Screen.

Input and editable fields are highlighted.

A. Fields that may be changed

Field	What to do
SSN / AMEND	Add or correct an SSN
N/C	Correct a name control
EIC	Add or delete an EITC-related child/credit use
Exemption / DEPD	Add or delete a dependent claim
CTC	Add or delete Child Tax Credit use
CCC	Add or delete Child Care Credit use
EDCR	Add or delete education credit use
ADPT CR	Add or delete adoption credit use

Enter A when adding credit use and D when deleting it.

If additional EIC is claimed on Form 1040-X, the additional EIC adjustment is entered in the EIC amount field.

B. Mandatory fields

These are the critical required inputs for an update.

Required information	Explanation
Amended filing status	Filing status after the amendment
Category code	Explains the type/source of adjustment
Claim amount	Net result of the adjustment
Schedule C indicator	Y if Schedule C changes are included; otherwise N

The claim amount cannot be blank or zero according to the listed error conditions.

C. Category codes — very important

Category	Meaning
EICX	Adjustment from an amended return / Form 1040-X
EICC	Adjustment from taxpayer correspondence
EICP	Adjustment from taxpayer telephone contact
EICN	Adjustment not related to EIC

On the Update Screen, the full category is represented by its final character:

X, C, P, or N.

Manual detail: the Update Screen identifies all four categories, but the general INVALID CATEGORY CODE error description lists only EICX, EICC, and EICP. This is an inconsistency in the source, so do not assume that EICN is universally invalid.

D. Additional financial fields

The screen also contains:

Field	Description
Original AGI	Adjusted Gross Income before adjustment
AGI adjustment	Increase or decrease in AGI
Original EIC	EIC originally reported
EIC adjustment	Change in EIC amount

Example:

• Original AGI = $20,000
• AGI adjustment = +$3,000
• Corrected AGI = $23,000

These numbers are only an illustrative calculation, not values taken from an IRS case.

E. Child age follow-up questions

After the changes are transmitted, DDBCK performs validation.

If an EITC qualifying child's age exceeds 19, the system may pause and ask whether the child is a student or disabled.

The documented prompts include:

• CH# AGE>19. IS QC A STUDENT?
• CH# AGE>19. IS QC DISABLED?
• CH# AGE > 24. IS QC DISABLED?

The user answers the question before validation continues.

These are system prompts, not a complete explanation of EITC eligibility law.

---

10. Schedule C Update Screen — when the claim involves business income

If the user enters Y for the Schedule C indicator, DDBCK opens a second update screen for additional Schedule C information.

This is important because changes in business income or expenses may affect AGI, EIC, and selection criteria.

The screen contains:

Information	Original amount	Corrected or adjustment amount
AGI	Original AGI	AGI adjustment
Schedule C gross receipts	Original receipts	Corrected receipts
Cost of goods sold	Original cost	Corrected cost
Home-office expense	Original expense	Corrected expense
Schedule C net profit	Original net profit	Corrected net profit
Wages	Original wages	Wage adjustment
EIC	Original EIC	Related information from the update process

Example

Suppose an amended return changes a taxpayer's Schedule C information:

Item	Original	Corrected
Gross receipts	$50,000	$55,000
Cost of goods sold	$10,000	$12,000
Home-office expenses	$3,000	$3,500

The employee enters the corresponding information from the return in the Schedule C screen. DDBCK then uses it as part of the validation process.

The manual lists three Schedule C-specific errors:

Error	Meaning
INVALID AMOUNT	An amount entered is invalid
NO SCHEDULE C DATA ENTERED	Schedule C was indicated, but necessary data was not entered
DDBNECXX READ ERROR	A file-reading problem occurred while processing Schedule C information

---

11. What exactly does DDBCK validate?

When the update is transmitted, DDBCK checks the new or changed information against its available data sources and business rules.

Check	What it looks for
TIN / SSN	Valid identification number information
Name Control	Whether identification information matches
Date of birth	Age-related issues
Date of death	Death-related issues
Duplicate TIN	Whether the same TIN was used elsewhere
DDB rules	Whether selection or validation rules were triggered
FCR	FCR-related conditions, as shown by the system
Citizenship	Possible citizenship issues
Schedule C filters	Schedule C-related conditions

DDBCK may display a problem if the name or TIN does not match INOLE, an individual is deceased or does not meet a relevant age criterion, duplicate TIN usage appears, or a DDB rule is broken.

The possible TIN/name/age results on Validation Page 1 include:

Message	Meaning
OK	No problem reported by that check
INVLD SSN	Invalid SSN
INVLD NC	Invalid Name Control
CCC AGE>12	Child care credit child is over age 12
CTC AGE>16	Child Tax Credit child is over age 16
EIC AGE>19	EIC child is over age 19
EIC AGE>24	EIC child is over age 24
DECD	Person died before the beginning of the tax year

Important distinction: Those age messages are historical system screening labels from this manual. They must not be treated as a complete statement of current tax-credit eligibility rules.

---

12. Validation Result Screen — the most important screen

The result appears after DDBCK has processed the changes.

The first page shows identification and age checks, financial information, processing status, and the instructions for handling the case.

The three main outcomes

Outcome 1 — OK to input ADJ54

The case does not meet the applicable examination-selection criteria. The employee may process the adjustment using normal procedures, provided eligibility and any other displayed conditions are satisfied.

Outcome 2 — Selected for examination

The case meets examination criteria. A result may read DDBCK SELECTED, REROUTE TO EITC.

DDBCK automatically generates an AIMS opening request through TC424 for the next posting cycle. The claim should not be processed through normal adjustment procedures.

Outcome 3 — Send to classification

A result may read SEND AS CAT A.

The employee sends the case for classification instead of processing the claim. Under this outcome, DDBCK does not generate an AIMS opening request.

What is the difference between examination and classification?

Examination	Classification
Case has been selected for examination	Case requires a classification decision
DDBCK generates an AIMS opening request through TC424	No automatic AIMS opening from this result
Reroute according to the displayed instructions	Send case to classification
Do not process the claim normally	Do not process the claim normally

Very important: The system displays its case-action instructions on Line 23 of Validation Page 1. That is the key place to look for the next processing action.

Other information on Page 1

The result screen also displays:

• Whether validation completed or failed.
• Original, adjusted, and corrected AGI.
• Original, adjusted, and corrected EIC.
• Wage information.
• Schedule C financial amounts.
• Results for the affected children and other TINs.
• Prompts regarding updates to DUPTIN.
• Messages explaining why a case was or was not selected.

What does DDBCV do differently?

DDBCV can display validation results for research, but the manual specifies that it does not save the data or send the case to examination.

This is a major difference between the two commands.

---

13. DUPTIN updates — an important decision after validation

When a claim is valid and the case is not selected for examination or classification, DDBCK can update the duplicate-TIN database, DUPTIN/DUPOL, to reflect the entered changes.

Normal situation

Validation passes → no examination/classification selection → appropriate DUPTIN information is updated.

What if the TIN or Name Control fails?

The system does not automatically make the update. Instead, it displays:

PROCESS UPDATES (Y/N)?

The employee has two possible paths:

Response or action	Meaning
Correct the information and retransmit	DDBCK runs validation again from the beginning
Enter Y and transmit	Directs DDBCK to process the DUPTIN update even if the TIN/name-control issue could not be corrected
Enter N	Does not proceed with the proposed update

The manual expressly describes the ability to answer Y when the incorrect TIN or name control cannot be corrected. This is an operational exception, not proof that the underlying claim is eligible.

The result may also indicate that updates were skipped.

---

14. Validation Result Screen — Page 2

After reviewing Page 1, the employee can press TRANSMIT to display Page 2.

Page 2 provides a more detailed explanation of the validation results.

What is shown?

Item	Meaning
FCR check	FCR conditions and affected children
Duplicate TIN check	Information about duplicate TIN use
Duplicate credits	Which credits were involved in the duplicate
DUPTIN updated Y/N	Whether the DUPTIN update occurred
Citizenship check	Whether a possible citizenship issue was detected
Schedule C filter	Whether a Schedule C-related condition was triggered
Check result	Repeats the selection/check result information
DDB rules fired	Which rules were triggered
Person affected	Which taxpayer or child triggered the rule

How to read the person codes

Code	Person
PRIM	Primary taxpayer
SECD	Secondary taxpayer
CH1	First child
CH2	Second child
CH3–CH6	Third through sixth child

DDB rule identifiers

The manual lists the following possible rule identifiers:

1, 2, 3, 4, 5x, 6x, 7x, 11, 12, 16x

The screen contains a rule explanation next to the rule number and affected person.

For example, a result identifying CH2 tells you that the second child is associated with the identified rule.

The PDF does not define the detailed criteria of every individual numbered DDB rule. Therefore, learning those internal criteria would require another applicable reference. It would be incorrect to invent their meanings.

---

15. All documented validation/check-result messages

The Validation Result Screen contains more detailed status messages than the three general outcomes explained earlier.

These are listed on Line 21 of Page 1 and repeated on Page 2.

Screen message	What you should understand
No problems found	No problem identified by that check
Plan met	A selection-plan-related result
Combat zone accept as filed	A combat-zone-related acceptance result
Not selected	Not selected under the applicable selection process
Not scored	Scoring was not performed
Fail validation	Validation failed
Under tolerance	A tolerance-related result
Under tolerance, release RI	A release-related result under tolerance
J2S after due dt	An internal timing/processing result
ME653 under 60d selected	A selection result associated with math error 653 and the stated time window
ME653 under 60d manual	A manual-handling result associated with math error 653
Selected exam	Selected for examination
Selected exam OR/AR	Examination selection with the displayed OR/AR designation
Auto select ME653>60D	Automatic selection associated with math error 653 and a period over 60 days
Send classification	Send the case to classification
POC QC/FS selected	An internal qualifying-child/filing-status-related selection result
QC certified	Qualifying-child certification-related status
ITIN	An ITIN-related result

Some messages are internal labels only. The PDF does not provide complete processing instructions for every label, so the exact Line 23 case action and related IRS procedures remain important.

16. All documented case-action messages — Line 23

This is one of the most useful reference tables in the entire guide.

Possible Line 23 message	What action it indicates
OK TO INPUT ADJ54 IF ELIGIBILITY MET	Adjustment may proceed if eligibility is satisfied
OK TO INPUT ADJ54 IF ELIGIBILITY MET, ENTER REASON CODE 103	Same general condition, plus Reason Code 103
OK TO INPUT ADJ54 IF ELIGIBILITY MET. FOLLOW IRM	Follow additional IRM requirements
OK to input ADJ54 - do not use BS74	Adjustment permitted, but do not use BS74
REJECT/DISALLOW CLAIM	Reject or disallow the claim
REJECT/DISALLOW 1 CHILD	Reject or disallow the claim for one child as directed
SELECTED, DDBCK REROUTE TO EITC xxSC	Selected case; reroute to the indicated EITC location
SELECTED, DDBCK REROUTE TO EITC BSC (9A OR 10A)	Selected case; follow the indicated EITC BSC routing
SELECTED, DDBCK REROUTE TO EITC PSC (9A OR 10A)	Selected case; follow the indicated EITC PSC routing
SELECTED, INPUT ADJ54 using BS 74 then route to EITC xxSC	Use the specifically instructed adjustment and routing sequence
SEND AS CATA	Send as Category A
QC CASE – FOLLOW IRM	Apply the IRM instructions for the qualifying-child case
POSSIBLE STATUTE OF LIMITATIONS, FOLLOW IRM PRIOR TO SENDING AS CAT A	Review the limitations issue before routing
FS JOINT TO SEPARATE AFTER THE DUE DATE. FOLLOW IRM	Follow filing-status procedures for this situation
FOLLOW IRM UNSUBSTANTIATED MATH ERROR PROCEDURES	Apply the specific math-error procedures
ACCEPT AS FILED, OK TO INPUT ADJ54	Accept as filed and process the stated adjustment
SEND AS CATA - SCH C	Send the Schedule C-related case as Category A
COMBAT ZONE CASE - FOLLOW IRM PROCEDURES	Use the special combat-zone procedures

Notice an important detail: not every selected case has the same instructions. One of the listed results specifically requires inputting ADJ54 with BS 74 before rerouting. Another explicitly says not to use BS74.

Therefore, do not rely solely on the word "selected." Read the full case-action message.

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17. DDBCS — Selection Setup Screen

Now let's understand the third command code.

DDBCS is not primarily used for entering a taxpayer's amended claim. Instead, it is used by headquarters to monitor and modify selection work plans.

The manual describes planning at these levels:

• Day by day.
• Week by week.
• Site by site.

DDBCS allows authorized headquarters personnel to review and change selection-related planning information, including plan volumes and cutoff scores.

Information displayed

Field	Purpose
Command parameter	Identifies the DDBCS request
Plan volume update request	Used to submit a plan-volume change
Cutoff score update request	Used to submit a cutoff-score change
Current cutoff score	Displays the current score threshold
Current processing cycle	Displays the processing cycle
AIMS opening date	Displays the related opening date
Cycle	Individual processing cycle
Plan volume (AR)	Planned AR volume
Selected count (AR)	Selected AR count
Plan volume (OR)	Planned OR volume
Selected count (OR)	Selected OR count

The manual uses the labels AR and OR in this screen but does not explicitly define them in its acronym table.

DDBCS routing rules

Two business rules control additional-case routing:

Situation	Routing instruction
No Schedule C issue	Route additional cases to another campus with remaining capacity, choosing the campus with the lowest inventory
Schedule C issue	Route additional cases to another SB/SE campus with remaining capacity

Simple example

Imagine three campuses still have capacity:

Campus	Current inventory
Campus A	120
Campus B	80
Campus C	150

If an additional case without a Schedule C issue needs routing, the rule favors Campus B, because it has the lowest inventory among campuses with capacity.

For a Schedule C-related case, the destination must additionally satisfy the SB/SE campus requirement.

The figures are illustrative. The PDF does not provide actual campus inventories.

Remember: DDBCK validates cases; DDBCS helps manage the selection workload and where additional cases are routed.

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18. Complete DDBCK error-message reference

These errors are important for both training and practical system use. I've grouped them by topic so they're easier to memorize while preserving the individual messages.

A. Access, database, and record errors

Error message	Meaning / response
CANNOT MODIFY RECORD - TC424 ALREADY SENT	The examination-selected record cannot be changed or deleted after the specified period has passed
DATABASE ACCESS ERROR -nnn	DB2 database system error; the manual directs contact with MCC Corporate Data Section, DB2 Administrator
DATABASE UNAVAILABLE, PLEASE TRY LATER	Temporary database unavailability; retry later
DDBNECxx READ ERROR	File-reading error while processing Schedule C data
NO RECORDS FOUND	No prior adjustment records were found
POSTED RETURN NOT FOUND FOR XXXXXXXX	No posted return was found on RTVUE for the entered SSN; verify the SSN
RECORD NOT FOUND	Requested history record does not exist
ONLY VIEW ALLOWED	The selected older record cannot be changed or deleted; change/delete is permitted only for the latest record

B. Date and identification errors

Error message	Meaning / response
DATE EARLIER THAN RETURN/PREV CLAIM	Claim date is earlier than the original return date or previous claim date
DATE OLDER THAN 18 MONTH	Amended-return received date entered is older than 18 months
INVALID DATE ENTERED	Invalid amended-return received date
DDBCK REQUIRES AN EDITED TIN	Enter TIN in edited format nnn-nn-nnnn
INVALID SSN	SSN must contain numeric digits
INVALID TAX PERIOD ENTERED	Tax period must be six numeric digits
INVALID MFT ENTERED	MFT must be 30
SECONDARY SSN REQUIRED	Spouse SSN is required when changing to filing status 2

C. Claim and credit errors

Error message	Meaning / response
ENTER A(ADD) OR D(DELETE)	Use A or D for credit-use changes
ENTER Y OR N	Response must be Y or N
INVALID CATEGORY CODE	Category code not accepted; general error text lists EICX, EICC, and EICP
INVALID CLAIM AMOUNT	Claim amount is blank or zero
INVALID EIC CHANGE, CANNOT BE NEGATIVE	EIC change entered is not allowed to be negative
INVALID FILING STATUS	Filing-status values must be 1–7
MATH ERROR 653 NOT PRESENT FOR EICC	EICC was entered without math error 653 on the module
MATH ERROR, FOLLOW IRM	Follow the relevant math-error procedures
NO SSN ENTERED FOR ADD	A credit was added without an SSN
USAGE NOT ENTERED FOR NEW SSN	A new SSN was entered without indicating any related credit usage

The MATH ERROR, FOLLOW IRM entry identifies these math error codes:

604, 605, 606, 616, 654–657, 667, 701–748

D. Limits on claimed children and dependents

Error message	Meaning
MORE THAN 2/3 CHILD CLAIMED FOR EIC	Too many qualifying children for the applicable EIC system limit
MORE THAN 2 CHILD FOR ADOPTION CR	More than two children claimed for adoption credit
MORE THAN 2 CHILD FOR CHILD CARE CR	More than two children claimed for child care credit
MORE THAN 6 SSN FOR EDUCATION CR	More than six SSNs claimed for education credit

These are the historical command-code validation limits stated in the manual; they should not be generalized into current legal limits for every tax year.

E. Request, paging, and completion errors

Error message	Meaning / response
INVALID PAGING REQUEST / PAGE NUMBER	Only pages 1 and 2 are available for the validation result
INVALID REQUEST	Request was not a recognized add, view, change, or delete request
REQUEST COMPLETE. NO CHANGES ENTERED	No changes were made on the Update Screen
REQUEST COMPLETE. UPDATES SKIPPED	DUPTIN update was skipped based on the response
REPEATER YYYYMM	A return-repeater condition for the indicated period

F. Additional errors and messages named in the screen exhibits

The screen descriptions contain additional messages beyond the general error list.

Message	What it indicates
DATE TOO OLD OR NEW	Entered date is outside the accepted range
CANNOT PROCESS MULTIPLE REQUEST	Multiple actions were requested together
NO ACTION ENTERED	No applicable action was submitted
INVALID EIC AMOUNT	Invalid EIC amount
ADDING EIC, BUT NO EIC ENTERED	EIC addition indicated without the required EIC value
INVALID, NET EIC AMOUNT IS < 0	Net EIC amount is negative
UNABLE TO VALIDATE TIN/NC ON CFOL, TRY LATER	TIN/name-control validation cannot currently be completed
INVALID CHILD - BIRTH YEAR	Child birth-year value failed validation
INVALID AMOUNT	Invalid amount on Schedule C update
NO SCHEDULE C DATA ENTERED	Required Schedule C data missing
REQUEST COMPLETE, UPDATE SKIPPED	Screen variant indicating update was skipped
INVALID PAGE NUMBER	Invalid validation page selection
POSTED RETURN NOT FOUND FOR (TAXPERIOD)	Return unavailable for the specified period

Easy troubleshooting method

When you receive an error, use this order:

1. Identification: Is the SSN edited correctly? Does the name control match?
2. Dates: Is the received date valid and properly ordered?
3. Required fields: Are filing status, category, claim amount, and Schedule C indicator completed?
4. Credit changes: Were A/D and the applicable amounts entered correctly?
5. Eligibility-related checks: Did an age, child-count, or other validation rule trigger?
6. Account conditions: Are there freezes, examination restrictions, or special IRM requirements?
7. Technical problems: Is the database temporarily unavailable, or did a read error occur?

If the issue is an input error, correct it and retransmit so the system can validate again. If the issue is an account restriction or processing instruction, follow the specified IRM instead of treating it as a simple data-entry problem.

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19. Technical screen reference — all seven exhibits

This section brings together the screen layouts described in Exhibits 2.4.58-1 through 2.4.58-7. It is particularly useful if you need to recognize where information appears on an IDRS terminal.

How to read the tables: Line means the numbered terminal-screen row. Position means the character position within that row.

I've kept the meaningful field positions and consolidated the repeated Literal entries, which simply identify fixed screen text rather than fields for taxpayer data.

Exhibit 1 — DDBCK Request Screen

Line	Position	Information
01	01–05	DDBCK / DDBCV command
01	07–17	Primary edited SSN
01	18	Validity digit: blank or *
01	19–26	MFT and tax period

Exhibit 2 — Return Summary Screen

General return information

Line	Position	Information
01	01–26	Command, SSN, validity digit, MFT and tax period
03	07–20	DLN of posted return
03	33–40	Return settlement date
03	53–60	Last claim date
03	67	Original filing status
03	79	Updated filing status

Taxpayer and child identification

Line	Position	Information
05	07–15	Primary SSN on return
05	17–25	Corrected primary SSN
05	28–31	Primary Name Control
05	34–41	Primary date of birth
05	43–50	Primary date of death
05	58	Primary exemption indicator
05	73	Primary education credit indicator
06	07–50	Secondary taxpayer identification, name control, and birth/death information in corresponding positions
06	58	Secondary taxpayer exemption indicator
06	73	Secondary education credit indicator
07–12	07–50	Up to six children's SSN, corrected SSN, name control, birth and death information

Child credit indicators

Position	Credit
54	EITC qualifying child
58	Dependent
63	Child Tax Credit
68	Child Care Credit
73	Education Credit
78	Adoption Credit

The same child-credit layout is repeated for up to six children.

Claim actions and messages

Line	Position	Information
15	05–12	New claim received date
15	24–26	ADD action
16–19	05–12	Previous claim received dates and VIEW selection
16	19–22	EDIT action
16	24–29	DELETE action
15–18	31–70	Additional account messages
21	01–15	REPEATER YYYYMM
24	01–80	Error messages after transmit

Exhibit 3 — Return Update Screen

Line	Position	Information
01	01–05	DDBCK
01	07–18	Primary SSN
01	19–26	MFT and tax period
03–12	—	Information corresponding to the Summary Screen
13	22	Category code: X, C, P, N
13	42–46	Claim amount
13	60	Schedule C indicator
15–18	31–70	Follow-up prompts, including qualifying-child age questions
16	11–17	Original AGI
16	20–26	AGI adjustment
17	14–17	Original EIC
17	22–26	EIC adjustment
24	01–80	Validation errors

Exhibit 4 — Schedule C Update Screen

Line	Position	Information
01	01–26	Command, SSN, validity digit, MFT/tax period
04	11–17	Original AGI
04	20–26	AGI adjustment
04	55–61	Original Schedule C gross receipts
04	64–70	Corrected gross receipts
05	14–17	Original EIC
05	55–61	Original cost of goods sold
05	64–70	Corrected cost of goods sold
06	55–61	Original home-office expense
06	64–70	Corrected home-office expense
07	55–61	Original net profit
07	64–70	Corrected net profit
08	11–17	Original wages
08	20–26	Wage adjustment
24	01–80	Validation error messages

Exhibit 5 — Validation Result Screen, Page 1

Line	Position	Information
01	01–26	Command, edited SSN, validity digit, MFT/tax period
03–13	Various	Summary Screen information
05–12	43–52	TIN, Name Control, and age-validation results
15–20	02–41	Validation messages
15	56–78	Original AGI, adjustment, corrected AGI
16	56–78	Original EIC, adjustment, corrected EIC
17	56–78	Original wages, adjustment, corrected wages
18	56–62, 72–78	Original and corrected Schedule C gross receipts
19	56–62, 72–78	Original and corrected cost of goods sold
20	56–62, 72–78	Original and corrected net profit
21	08–41	Validation-completed message
21	42–68	Check-result message
22	10–31	DUPTIN process-update prompt
22	33	Y/N update response
23	10–45	Case-action instruction
24	01–40	Error or response text
24	45–55	Page information
24	59–68	Paging command

Exhibit 6 — Validation Result Screen, Page 2

Line	Position	Information
01	01–26	Command and return identification
04	02–23	FCR-related condition and affected children
05	02–23	Duplicate-TIN-use condition
05–06	26–77, as applicable	Duplicated children and credits
06	02–18	DUPTIN updated Y/N
07	02–26	Possible citizenship issue
08	02–41	Check result
09	02–32	Schedule C filter result
12–22	07–09	DDB rule that fired
12–22	14–17	Person associated with the rule
12–22	20–29	Rule explanation
24	45–55	Page information
24	59–68	Paging command

Exhibit 7 — DDBCS Selection Setup Screen

Line	Position	Information
01	01–05	DDBCS
01	07–21	Command parameter
05	07–53	Plan-volume update request
06	07–33	Cutoff-score update request
08	41–44	Current cutoff score
09	36–41	Current processing cycle
09	67–76	AIMS opening date
13–23	06–11	Cycle
13–23	16–19	Plan volume (AR)
13–23	23–26	Selected count (AR)
13–23	33–36	Plan volume (OR)
13–23	40–43	Selected count (OR)
24	01–40	Message

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20. Important operational rules to memorize

Here are the rules that connect the entire manual.

Situation	Rule to remember
Need to validate and update an amended claim	Use DDBCK with appropriate authorization
Need research without saving changes	Use DDBCV
Need headquarters selection/workload planning	Use DDBCS
Adding credit use	Enter A
Deleting credit use	Enter D
Reviewing original credit use	Look for Y
Original credit was disallowed	Look for x
New claim	Use ADD with the received date
Correcting the latest existing claim	Use EDIT
Reviewing an older claim	Use VIEW
Schedule C changes included	Enter Y for Schedule C
TIN/name-control validation fails	Correct and revalidate, or handle the DUPTIN prompt under the documented instructions
No examination criteria met	Follow the displayed normal adjustment instructions
Selected for examination	Follow the routing instructions; TC424/AIMS processing applies as described
Sent to classification	Do not normally process the claim; send for classification
STOP displayed	Normal claim input is disabled
Need details of fired DDB rules	Review Validation Page 2
Need the next processing action	Read Line 23 on Validation Page 1

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21. Full worked example — from beginning to end

Let's bring everything together with one hypothetical case.

Situation

A taxpayer originally filed a return claiming one qualifying child.

Later, they file Form 1040-X requesting additional EIC related to a second child.

The employee needs to review the new claim using DDBCK.

Step 1 — Retrieve the return

Enter DDBCK with the appropriate edited primary SSN and return identification. The Summary Screen displays the original return, dependents, filing status, and previously claimed credits.

Step 2 — Review the original information

Confirm that the original child is present, check the credit indicators, and review whether any account warnings, previous claims, or STOP condition exists.

Step 3 — Add the new claim

Enter the amended claim received date, choose ADD, and transmit.

Step 4 — Enter amended information

Add the second child's SSN and Name Control, use A in the appropriate EIC child-credit field, enter the additional EIC amount, amended filing status, category EICX, net claim amount, and Schedule C indicator N if no Schedule C changes are involved.

Step 5 — Run validation

Transmit the update. DDBCK checks the submitted information, including name/TIN matching, age-related information, duplicate usage, and applicable DDB rules.

Step 6 — Review the results

On Page 1, read the identification results, financial changes, validation status, and Line 23 instructions. Use Page 2 to identify any duplicate-TIN issues or fired rules.

Step 7 — Follow the decision

If permitted, process the normal adjustment. If selected for exam, follow the examination instructions. If referred to classification, send the case there. Address any DUPTIN update prompt as applicable.

What this example teaches

DDBCK is not simply an SSN-checking tool. It is a workflow for reviewing an amended claim, validating changed information, checking selection rules, and communicating the required case action.

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22. Additional manual details

To round out the reference, here are the administrative details from the document:

Item	Information
Manual number	IRM 2.4.58
Manual area	Part 2, Information Technology
Chapter	Chapter 4, IDRS Terminal Input
Section	Section 58, DDBCK / DDBCV / DDBCS
Manual transmittal	March 31, 2025
Effective date	March 31, 2025
Previous version superseded	December 20, 2024
Policy owner	Taxpayer Services
Program owner	Taxpayer Services
Related resource	IRM 2.4.85
Authority section	Lists “None”; no separate authority is identified there
Page last reviewed or updated	April 30, 2026

The March 2025 revision documented three material changes: updating the RICS wording in the responsibilities section, adding RICS to the acronym table, and updating the Return Update Screen layout in Exhibit 2.4.58-3.

The purpose of this IRM is to instruct IRS personnel in using these systems. It is not a complete standalone authority for substantive credit eligibility, examination, statute-of-limitations, or other related tax-law procedures.

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23. Test yourself — practice questions

Try answering each question before reading its answer. These 15 questions cover the key ideas from the guide.

Question 1: What is the main purpose of DDBCK?

Answer: To validate additional children and credits claimed on amended returns and related claims, record appropriate changes, and provide processing or referral instructions.

Question 2: What is the difference between DDBCK and DDBCV?

Answer: DDBCK supports validation and updates. DDBCV is for viewing/research without saving the changes or sending cases to examination.

Question 3: What does DDBCS do?

Answer: It is a headquarters selection setup system used to monitor and modify work plans, volumes, cutoff scores, and case routing.

Question 4: What do Y, A, D, and x mean?

Answer: Y = claimed on original return; A = added later; D = deleted later; x = disallowed when the original return was filed.

Question 5: Which four fields are required on the Return Update Screen?

Answer: Amended filing status, category code, claim amount, and Schedule C Y/N indicator.

Question 6: What does EICX mean?

Answer: An adjustment originating from an amended return or Form 1040-X.

Question 7: What happens when the Schedule C indicator is Y?

Answer: A second update screen appears for Schedule C amounts such as gross receipts, cost of goods sold, home-office expenses, and net profit.

Question 8: Where are the main case-action instructions displayed?

Answer: Line 23 of Validation Result Screen Page 1.

Question 9: What happens when a case is selected for examination?

Answer: The manual describes an automatic AIMS opening request through TC424 for the next posting cycle, with the claim handled under the displayed examination instructions rather than normal processing.

Question 10: What is different when a case is sent to classification?

Answer: The case is forwarded for classification without normal claim processing, and DDBCK does not generate an AIMS opening request for that result.

Question 11: What should you look at on Validation Result Page 2?

Answer: FCR, duplicate TIN, citizenship, Schedule C filter, rule identifiers, affected persons, and whether DUPTIN was updated.

Question 12: What does PROCESS UPDATES (Y/N)? mean?

Answer: A prompt related to proceeding with a DUPTIN update when TIN or name-control validation has failed. Corrections can be retransmitted, and the manual documents a Y override in the specified situation.

Question 13: Can you edit any of the four previous claims?

Answer: No. Previous claims may be viewed, but only the latest record is eligible for normal change or delete requests.

Question 14: What does STOP mean?

Answer: The system has disabled normal claim-date input due to specified account or tax-period conditions, such as an L freeze, TC290, an EITC ban, or an old tax period.

Question 15: What is the DDBCS routing rule for a case with a Schedule C issue?

Answer: Route it to another SB/SE campus that still has capacity.

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24. Final revision sheet — the whole topic at a glance

DDBCK / DDBCV / DDBCS Cheat Sheet

Term	Remember
DDBCK	Validate and update claims
DDBCV	View/research without saving
DDBCS	Selection and workload planning
Form 1040-X	Amended individual income tax return
Y / A / D / x	Originally claimed / added / deleted / disallowed
EICX	Amended return
EICC	Taxpayer correspondence
EICP	Taxpayer phone contact
EICN	Non-EIC adjustment
Schedule C = Y	Open additional Schedule C input
Validation Page 1	Identification, amounts, status, case action
Line 23	Key case-action instruction
Validation Page 2	Detailed checks and DDB rule results
TC424	AIMS opening request for examination selection
SEND AS CAT A	Forward for classification
ADJ54	Normal adjustment processing where permitted
DUPTIN / DUPOL	Duplicate TIN checking and updates
STOP	Normal input disabled

The single most important idea to remember

DDBCK checks the amended claim, validates the changed information, and tells the IRS employee what processing action to take. DDBCV is the research-only version, and DDBCS manages selection work plans.

If you understand the workflow, memorize the indicators and category codes, know what appears on each validation page, and can interpret the case-action messages, you will understand the central content of IRM 2.4.58.

Study recommendation: Read Sections 1–14 first to understand how the system works. Then study Sections 15–19 for detailed status messages, errors, and technical screen layouts. Finally, complete the questions in Section 23 without opening the answers. The guide covers the substantive instructions and technical reference information in the supplied manual, with repeated fixed screen labels consolidated for readability.