Part of Diagnostic Imaging Data Set (DIDS) v2.0 user guidance
Data item guidance
This section provides additional guidance with regard to data items included within the TOS.
Error messages
The DIDS v2.0 ETOS, provides details of the validations which will take place when DIDS v2.0 data is received by NHS England. This includes the relevant error codes and error messages where the validations are triggered.
This includes:
a) Validations on specific data items which would cause the file to be rejected.
b) Validations on specific data items which would generate a warning to check the data quality for the data submitted.
c) Further validations which take place, for example across multiple data items (defined in the “Additional File-level Rejects” tab).
Following submissions, the data quality feedback the submitter receives via NDIT can be looked up within the ETOS, to help ascertain the reason for the error message(s) to support resolution of data quality issues and timely resubmission of data.
Timestamps
A number of data items were amended to ‘timestamps’ within DIDS v2.0, to increase the accuracy of data recorded and for consistency across other data sets. One example of this is the SERVICE REPORT ISSUE TIMESTAMP data item.
The timestamp fields should always show the time ‘as shown on the clock’. For example, a submitted value of ‘2025-05-31T23:30:00+01:00’ is showing that the time when an activity took place was 23:30, during part of the year when british summer time applies.
As mentioned on the relevant NHS Data Model and Dictionary pages, the only valid offset times (at least for activity taking place in this country, which it all should be for DIDS) are ‘+01:00’, ‘+00:00’ or ‘-00:00’ (or a ‘Z’).
The following principles should be applied:
The time zone offset should be factored into any date comparison validations, such as to check whether a timestamp is after the end of the reporting period. Dates should not need to be converted back to GMT; however, some logic may need to be developed to handle comparisons between timestamps and reporting periods that fall on the day that the clocks change.
Offset times other than ‘+01:00’, ‘+00:00’ or ‘-00:00’ (or ‘Z’) will be rejected in DIDS data submitted, and inappropriate offset times (e.g. ‘+00:00’ when british summer time applies) may also be rejected/be highlighted as a data quality issue.
Breakdown of data Items by data group
Data items are listed in the following groups using the NHS Data Model and Dictionary data element names. The electronic copy of this document includes hyperlinks to the corresponding entries in the NHS Data Model and Dictionary where formal definition of the data item can be found and relationships with other data elements and attributes are defined.
Users should be aware that links to new data items will not be available immediately following ISN publication.
This document is continually under review. Where data items do not have additional guidance, we will amend if suitable guidance becomes available.
Additional information on individual data items, can be found via the NHS Data Model and Dictionary. Within the Diagnostic Imaging Data Set section, individual data items can be found using the search bar.
DIDS000 Header
In an Extensible Markup Language (XML) submission this group appears once at the top of the file. For a Comma-Separated Values (CSV) submission this data must be repeated exactly in every row of the file. The CSV file will be rejected if any row from this group differs or doesn’t match in any way.
Description
The Header group includes metadata relating to the submission, including which organisation and reporting periods the data relates to, the primary data collection system in use and the date/time the file was created. All data items are mandatory. Any blank, NULL or otherwise missing or invalid values will result in the submission file being rejected.
Additional notes on data items
| Data item number | Additional notes |
|---|---|
| DATA SET VERSION NUMBER | The version of the DIDS that the submission file is for. The current version of the data set is v2.0. ‘2.0’ must be entered as the version number, otherwise your file will be rejected. |
| ORGANISATION IDENTIFIER (CODE OF PROVIDER) |
This is the ORGANISATION IDENTIFIER of the ORGANISATION acting as a Health Care Provider. This is the organisation Identifier that will be concatenated with any Local Patient Identifiers to form a unique "Local Patient Identifier" within the national database. |
| ORGANISATION IDENTIFIER (CODE OF SUBMITTING ORGANISATION) |
This field will normally contain the same Identifier as ORGANISATION Identifier (CODE OF PROVIDER), which is used to determine the ORGANISATION IDENTIFIER of the ORGANISATION acting as a Health Care Provider. It may be appropriate for the codes to differ; however, provider and submitter should ensure that appropriate governance is in place for the flow of patient identifiable data between the two organisations. Further information can be found on the Code of practice for handling information in health and care. |
| PRIMARY DATA COLLECTION SYSTEM IN USE |
This is a free text field. Where multiple systems are in use, please indicate the primary system in use, from which the highest number of records is extracted. |
| REPORTING PERIOD START DATE | The reporting period start date to which this file refers, i.e. the first calendar day of the reporting month (for example 2026/04/01). |
| REPORTING PERIOD END DATE | The reporting period end date to which this file refers, i.e. the last calendar day of the reporting month (for example 2026/04/30). |
| DATE AND TIME DATA SET CREATED | The date and time the upload file was created. DIDS management systems should have an automatic ‘date and time data set created’ field. If a DIDS management system does not automatically generate this field, it will need to be manually populated. |
DIDS001 Master Patient Index
Description
The Master Patient Index group includes data about the patient, including the Local Patient Identifier (Extended), NHS Number (if known), Person Birth Date etc. Only LOCAL PATIENT IDENTIFIER (EXTENDED) & ORGANISATION IDENTIFIER (LOCAL PATIENT IDENTIFIER) are mandatory. Any blank, NULL or otherwise missing or invalid values in these fields will result in the submission file being rejected. All required fields should be submitted where they apply.
Additional notes on data items
| Data item name | Additional notes |
|---|---|
| Local Patient Identifier (Extended) |
The Local Patient Identifier (Extended) is used to uniquely identify a patient within the Health Care Provider. No patient can have more than one Local Patient Identifier (Extended). This can be checked by looking at data items such as NHS number, postcode and date of birth. To avoid the incorrect linkage of records the Local Patient Identifier (Extended) must not be reused i.e. it should only ever relate to one patient. This ensures that data relating to more than one patient does not get incorrectly identified as belonging to a single patient in DIDS |
| ORGANISATION IDENTIFIER (LOCAL PATIENT IDENTIFIER) |
This identifies the Local Patient Identifier issuing organisation, for example: where organisations have gone through a merger or split.
|
| NHS Number |
Where the NHS Number is not known, this should be left blank. When an NHS number is provided it must pass the modulus 11 check. When an NHS number is provided it should have a corresponding status indicator code. NHS number is the primary source of identification for patients in England and Wales and should be submitted; however, it is accepted that occasionally a patient will not have an NHS number therefore this data item is ‘Required’ and not ‘Mandatory’ in DIDS, which ensures that data for the patient can still flow. Although it is not a mandated field, data quality reports will be produced with regard to completeness of this field. Further guidance about NHS Numbers is available. |
| NHS NUMBER STATUS INDICATOR CODE |
This data item is ‘Required’ however it should always be completed, irrespective of whether an NHS number is present. In cases where a patient’s NHS number is unavailable (which may be because the patient does not possess one) data providers should submit a null NHS number and [07] Number not present and trace not required in NHS Number Status Indicator Code. In most cases, this data item will be flowed with value [01] - Number present and verified. The [01] will indicate that the data provider has validated the number against the central Patient Demographics Service (PDS) and therefore facilitates reliable data linkage. Data providers may flow data for patients with an NHS number status indicator code other than [01] and they will be accepted, however, reports that need reliable linkage may exclude these records (unless reliable linkage is available via LOCAL PATIENT IDENTIFIER (EXTENDED). Note to users creating .csv format in Excel; this column should be formatted as text to retain the leading zero where present in the National Codes. |
| PERSON BIRTH DATE |
Every effort should be made to identify the patient’s correct date of birth, or date that the patient has estimated to be their date of birth. However, where the patient’s DOB cannot be determined precisely, estimation should be provided. If it is not possible/appropriate to estimate, then the data item should be left blank (Null). Estimates should not change once they have been made. Once the actual DOB is identified, it should be recorded and submitted correctly. When estimating a patient’s DOB a consistent approach should be used, for example: use 1 July if only the year is known, 15th of the month if only the month is known, 1 January for beginning of the year, 31 December for end of the year, 25 December for Christmas |
| Ethnic Category |
The information recorded about the patient’s ETHNIC CATEGORY must be obtained by asking the PATIENT. Capture and submission of Ethnic Category within the DIDS is required for ALL patients, and not only those subject to an inpatient stay, in order to support ethnic monitoring as required of public bodies under the Race Relations Amendment Act 2000. Codes [Z] – Not Stated, and [99] - Not Known should be applied as follows: The [Z] 'Not Stated' national code should only be used where the patient had been asked and had declined either because of refusal or genuine inability to choose. The [99] 'Not known' national default code should be used where the patient had not been asked, or the patient was not in a condition to be asked. For example unconscious. |
| ETHNIC CATEGORY 2021 |
This is a placeholder data item to accommodate the classification used for 2021 census. Note: This item has not been approved by the Data Assurance Board. It has been introduced to provide advance notice to data providers and IT system providers of the intention to report this item at a later date. This item should not be submitted until further development by NHS England has been undertaken. |
| PERSON STATED GENDER CODE |
The NHS data dictionary definition of this item is: The gender of a person. Person Stated Gender Code is self-declared or inferred by observation for those unable to declare their Person Stated Gender. This is the existing code used in Personal Demographics Service (PDS) which records somebody’s stated gender. (This does not have to be their birth gender or their legal gender). This will record the person’s gender at their GP (e.g. male or female) and will also match the PDS data which is provided by the GP. Please refer to the Technical Output Specification and the guidance on our webpages for additional details. Further details on Gender Identity are available. National Code X 'Not Known (PERSON STATED GENDER CODE not recorded) ' means that the sex of a PERSON has not been recorded National Code 9 'Indeterminate' means indeterminate, i.e. unable to be classified as either male or female. |
| Postcode of Usual Address |
See the ‘Technical Glossary’ tab within the Technical Output Specification for further details regarding acceptable postcode formats and validations applied at the submission portal. Where the person has no fixed abode, this should be recorded as ZZ99 3VZ. If the postcode is unknown ZZ99 3WZ should be used. For overseas residents, please use the pseudo country postcode found in the ‘Country names and pseudo country postcodes in pseudo country postcode order’ file on the NHS Digital web page: Data supplied by the Office of National Statistics. The postcode will be recorded in the format ZZ99 xxZ, where xx denotes the country pseudo postcode. |
| GENERAL MEDICAL PRACTICE CODE (PATIENT REGISTRATION) |
see GENERAL MEDICAL PRACTICE CODE (PATIENT REGISTRATION) for information on the use of the default codes. We do not at this time recommend using the new ANANA codes for recording branch surgery codes. Please continue to submit the parent GP codes as these will still continue to be assigned to the correct ICB. Further information can be found on the NHS Data Model and Dictionary. For more general information on default codes, please visit Organisation Data Service Default Codes |
DIDS002 Referral
Description
The Referral group includes data about the referral. Only PATIENT SOURCE SETTING TYPE (DIAGNOSTIC IMAGING) is mandatory. Any blank, NULL or otherwise missing or invalid values in this field will result in the submission file being rejected. All required fields should be submitted where they apply.
Each record submitted in DIDS must have data about the referral.
Additional notes on data items
| Data item name | Additional notes |
|---|---|
|
PATIENT SOURCE SETTING TYPE (DIAGNOSTIC IMAGING) |
The type of setting that the PATIENT came from at the time of request for Diagnostic Imaging for use in the Diagnostic Imaging Data Set. National Code ‘08’ ‘Screening Programme Setting’ applies where the referral request for Diagnostic Imaging came from a Screening Programme Setting. Note to users creating .csv format in Excel; this column should be formatted as text to retain the leading zero where present in the National Codes. |
|
REFERRER CODE (DIAGNOSTIC IMAGING) |
REFERRER CODE (DIAGNOSTIC IMAGING) is the code of the PERSON making the REFERRAL REQUEST for the Diagnostic Imaging. Must be in one of the following formats. C followed by up to 7 digits (consultant) CH followed by up to 6 digits (chiropodist) D followed by up to 7 digits (dentist) DT followed by up to 6 digits (dietician) CD followed by up to 6 digits (dental consultant) G followed by up to 7 digits (GP England and Wales) PH followed by up to 6 digits (Physiotherapist) S followed by up to 7 digits (GP Scotland) SL followed by up to 6 digits (speech language therapist) [Z as 1st character], [E,N,S or W as 2nd character], followed by up to 6 digits (GP N.Ireland) 2 digits, followed by one letter, followed by 4 digits, followed by one letter [NNLNNNNL] (Nurse) NOTE: Referrer Code for a GP must be their GMP (General Medical Practitioner) code and not their GMC (General Medical Council) code. A GP may have more than one GMP code if they operate from multiple practices. If the person making the referral request is from a healthcare profession not listed above, or their code does match the above format (e.g. paramedic starting PA) then the default code of H9999998 - Other health care professional must be submitted. A full list of defaults is available from the NHS Data Model and Dictionary. |
|
TREATMENT FUNCTION CODE (REFERRAL FOR DIAGNOSTIC IMAGING) |
TREATMENT FUNCTION CODE (REFERRAL FOR DIAGNOSTIC IMAGING) is the ACTIVITY TREATMENT FUNCTION CODE under which the CARE PROFESSIONAL or SERVICE has been treating the PATIENT before referring the PATIENT for Diagnostic Imaging. Further information on the groupings and scope of each TREATMENT FUNCTION CODE is provided in the NHS Data Model and Dictionary at Main Specialty and Treatment Function Codes Table |
|
ORGANISATION IDENTIFIER (REFERRING ORGANISATION) |
ORGANISATION IDENTIFIER (REFERRING ORGANISATION) is the ORGANISATION IDENTIFIER of the ORGANISATION from which the referral is made, such as a GP Practice, NHS Trust or NHS Foundation Trust. |
|
SERVICE REQUEST PRIORITY TYPE |
The priority of a SERVICE REQUEST. In the case of SERVICES to be provided by a CONSULTANT, it is as assessed by or on behalf of the CONSULTANT. National Code 'Urgent' should be used where the SERVICE REQUEST is defined as clinically urgent, but it does not fall under the criteria for 'Urgent Suspected Cancer or Breast Symptomatic'. National Code 'Urgent Suspected Cancer or Breast Symptomatic' should be used where either the:
|
|
DIAGNOSTIC TEST REQUEST DATE |
The date a DIAGNOSTIC TEST REQUEST was made. |
|
DIAGNOSTIC TEST REQUEST TIME |
The time a DIAGNOSTIC TEST REQUEST was made. |
|
DIAGNOSTIC TEST REQUEST RECEIVED DATE |
For the Diagnostic Imaging Data Set, DIAGNOSTIC TEST REQUEST RECEIVED DATE is the date the DIAGNOSTIC TEST REQUEST was received by the Imaging Department. |
|
DIAGNOSTIC TEST REQUEST RECEIVED TIME |
For the Diagnostic Imaging Data Set, DIAGNOSTIC TEST REQUEST RECEIVED TIME is the time the DIAGNOSTIC TEST REQUEST was received by the Imaging Department. |
DIDS003 Activity
Description
The Activity group includes data about the activity in the reporting period. Only RADIOLOGICAL ACCESSION NUMBER, ORGANISATION SITE IDENTIFIER (OF IMAGING), CODED PROCEDURE START TIMESTAMP & CODED PROCEDURE END TIMESTAMP are mandatory. Any blank, NULL or otherwise missing or invalid values in these fields will result in the submission file being rejected. All required fields should be submitted where they apply. A valid value for EITHER the CODED PROCEDURE (NICIP) or CODED PROCEDURE (SNOMED CT) data item must be submitted.
Additional notes on data items
| Data item name | Additional notes |
|---|---|
|
RADIOLOGICAL ACCESSION NUMBER |
RADIOLOGICAL ACCESSION NUMBER is the unique record number in the local Radiological Information System (RIS) for the Diagnostic Imaging. Each accession number must be unique within the submission.. Duplicate accession numbers will not pass validation. |
| ORGANISATION SITE IDENTIFIER (OF IMAGING) |
ORGANISATION SITE IDENTIFIER (OF IMAGING) is the ORGANISATION SITE IDENTIFIER of the ORGANISATION SITE where the Diagnostic Imaging took place. This refers to the Organisation Site Identifier of image acquisition rather than image reporting. |
|
CODED PROCEDURE (NICIP) |
CODED PROCEDURE (NICIP) is the NICIP CODE which is used to identify a Patient Procedure. |
|
CODED PROCEDURE (SNOMED CT) |
CODED PROCEDURE (SNOMED CT) is the SNOMED CT® concept ID which is used to identify a Patient Procedure. |
|
CODED PROCEDURE START TIMESTAMP |
CODED PROCEDURE START TIMESTAMP is the date, time and time zone that the Patient Procedure was started by a CARE PROFESSIONAL. This does not include pre-test or pre-procedure activity before the patient is present. This does include the administration of any liquids or other substances to the patient which are required for the patient procedure. |
|
CODED PROCEDURE END TIMESTAMP |
CODED PROCEDURE END TIMESTAMP is the date, time and time zone that the Patient Procedure was completed by a CARE PROFESSIONAL. This includes initial post-processing that may be undertaken relating to the procedure. See defining activity in a reporting period for more information. |
|
SERVICE REPORT ISSUE TIMESTAMP |
For the Diagnostic Imaging Data Set, SERVICE REPORT ISSUE TIMESTAMP is the date, time and time zone when the CARE PROFESSIONAL issues the radiology report. This captures the timestamp the completed radiology report is issued. Where there is a subsequent addendum to the report this timestamp should not be updated in DIDS. |
|
DIAGNOSTIC IMAGING CANCER INDICATION CODE |
An indication of whether a PATIENT undergoing Diagnostic Imaging has been found to have suspected or confirmed Primary Cancer or Cancer Recurrence. This is a Pilot data item. For further guidance on submitting this, please see the NDRS website. Note to users creating .csv format in Excel; this column should be formatted as text to retain the leading zero where present in the National Codes. |
|
GENERAL ANAESTHETIC ADMINISTERED INDICATOR |
An indication of whether a general anaesthetic was administered to a PATIENT in order to carry out the Patient Procedure. This data item only indicates where a general anaesthetic was administered to carry out the patient procedure. It does not indicate where other types of anaesthetics (such as Local anaesthetics or Regional anaesthetics) are administered. Where this data item is not submitted it will be processed as null/no data rather than ‘N’. |
|
REFERRER RADIOLOGY PROCEDURE EVALUATION INDICATOR |
An indication of whether the responsibility for the clinical evaluation of the Patient Procedure was passed to the referrer because the examination record does not have a formal radiology report issued by the Radiology Department. Where this data item is not submitted it will be processed as null/no data rather than ‘N’. |
|
DIAGNOSTIC IMAGING ACTIVITY CATEGORY |
The category of diagnostic imaging activity under which the patient was seen. Categories are defined in the Diagnostic Waiting time and Activity (DM01) guidance. Note to users creating .csv format in Excel; this column should be formatted as text to retain the leading zero where present in the National Codes. |
|
DIAGNOSTIC IMAGING WAITING LIST CLOCK START DATE |
Diagnostic Imaging Waiting List Clock Start Date is the date that the waiting list clock started, where the DIAGNOSTIC IMAGING ACTIVITY CATEGORY National Code is 'Diagnostic Waiting List'. The clock start date is defined in the Diagnostic Waiting time and Activity (DM01) guidance |
|
PLANNED DIAGNOSTIC DUE DATE |
Planned Diagnostic Due Date is the date that the planned Diagnostic Imaging test was due, where the DIAGNOSTIC IMAGING ACTIVITY CATEGORY National Code is 'Planned Diagnostic'. |
Last edited: 23 March 2026 1:25 pm