eCTD Module 1 Structure: FDA Section Lookup

FDA eCTD Module 1 contains the regional administrative and prescribing information associated with an application. For the sections most often confused, the current FDA hierarchy is 1.12.14 Environmental analysis; 1.15 Promotional material; 1.16 Risk management plan, including REMS at 1.16.2; and 1.17 Postmarketing studies. The general investigational plan for an initial IND is 1.20.

This is a section lookup reference, with selected lower-level entries and placement examples. It is not the complete FDA hierarchy or an application-specific checklist. Use the Module 1 requirements and preparation guide for applicability and regional preparation, and the five-module structure guide for the wider dossier.

Scope and governing versions

The entries were checked on October 6, 2026 against two separate FDA documents:

• For eCTD v3.2.2: Comprehensive Table of Contents Headings and Hierarchy, version 2.3.5, February 18, 2025, Module 1 on printed pages 1–4.
• For eCTD v4.0: eCTD v4.0 Comprehensive Table of Contents Headings and Hierarchy, version 2.2, February 2025, Module 1 on printed pages 1–4. FDA lists support beginning February 18, 2025.

Most locations shown below agree across those documents. The naming and other version-specific differences are called out explicitly. Do not confuse the version of a table-of-contents document with the eCTD format version or a regional DTD version.

Module 1 is regional. ICH's M4 organization guidance describes Modules 2–5 as the common technical structure while leaving Module 1's content and format to regional authorities. An FDA section number is therefore not a universal EU, Canadian, or Japanese placement instruction. See M4 Organization, October 2017, section IV.

FDA Module 1: top-level section map

This table covers 1.1 through 1.20. Descriptions are navigation aids; use the applicable FDA hierarchy for the full official subheading list and any associated attributes or keywords.

Source for this map: the v3.2.2 hierarchy and v4.0 hierarchy, printed pages 1–4. A section's presence here does not mean every sequence should contain it.

Selected document-to-section lookups

These entries resolve common placement questions. Unless marked otherwise, the numbered locations are present in both checked hierarchies.

Administrative records, references, and meetings

The environmental entry is 1.12.14, not 1.17. “Other correspondence” is a parent heading with specific children; it does not mean the destination should be chosen without inspecting those children. Likewise, a letter of authorization and a statement of right of reference have distinct entries. See the v3.2.2 hierarchy, printed pages 1–2.

If a letter also creates response work, record that obligation separately from its filing location. The authority-response workflow guide addresses ownership and evidence; a correctly filed document is not a completed response.

Labeling

“Labeling” is not sufficiently precise to select a final destination. Establish whether the file is draft or final, what kind of labeling it contains, and its submission purpose. The hierarchy distinguishes a final package insert from final labeling text; do not collapse those entries merely because both files contain text. Source: FDA v3.2.2 hierarchy, printed page 3, and the matching v4.0 labeling entries.

The scientific support for a labeling statement belongs in the appropriate technical content, even when the label itself is in Module 1. Placement does not establish agreement between the label and that evidence. Evaluate such discrepancies separately through regulatory document QC.

REMS and postmarketing correspondence

REMS is a child of 1.16, while promotional material is 1.15. The annual-report status entry 1.13.12 and the postmarketing-correspondence entries 1.17.1/1.17.2 answer different document-purpose questions. A full study report is another document type again. Source: FDA hierarchy, printed pages 3–4.

Version-specific entries you must not merge

The following differences were checked independently in each hierarchy. A blank or absent source entry is not permission to invent a corresponding destination.

These are differences in the published lookup documents, not a determination of how every possible legacy document must be submitted. If the v3.2.2 hierarchy lacks the specific entry you expected, obtain the applicable instruction instead of importing a v4.0 section number. Compare v3.2.2 printed pages 2 and 4 with v4.0 printed pages 2 and 4.

A heading is not the technical encoding

In v3.2.2, check the regional backbone and form exceptions

FDA's Module 1 Backbone Specification v2.6, March 31, 2025 describes us-regional.xml, with administrative metadata and regional content organized separately. Its example location is 0006/m1/us/us-regional.xml, referenced from the corresponding index.xml. This is a v3.2.2 technical example, not a v4.0 file recipe. See specification sections Introduction and II.

Do not translate the high-level “1.1 Forms” label into “put every form under the same XML heading.” Table 10 of that specification distinguishes:

• FDA 1571 and 356h: the form element within submission-information in the administrative portion.
• Patent forms FDA 3542a and 3542: the patent-information element under 1.3.5.1.
• Other forms: the form element under m1-1-forms, using the applicable current form-type list.

These are v3.2.2 encoding instructions from Table 10, printed page 18. They do not supply a v4.0 Context of Use code. FDA also instructs v3.2.2 submitters to omit empty content headings; a complete reference map is not a direction to populate every branch.

In v4.0, distinguish displayed headings from message metadata

The v4.0 hierarchy warns that keyword placement in a viewing tool can differ from keyword assignment in the XML message. It marks required and optional keywords and describes inheritance from higher headings. Therefore, a correct-looking display does not by itself prove that the message's metadata is correct. See v4.0 hierarchy, Instructions to Reader.

For actual encoding, use the current implementation guide, controlled vocabulary, and schema resources linked from FDA's v4.0 standards page. The regional implementation guide checked here is v1.9, August 2026; FDA lists its support beginning September 28, 2026. Its submission-unit and Context of Use model is not the v3.2.2 regional-backbone model.

FDA currently accepts v4.0 for new eligible applications; its notice says forward compatibility for existing v3.2.2 applications is not yet available. Published implementation instructions or samples are not, on their own, permission to transition an existing application. Check FDA's current eCTD notice.

Worked placement review

This fictional manifest tests the lookup only. It contains no real patient data and is not a complete or validated submission.

For the two matching rows, the conclusion is deliberately narrow: the heading fits the supplied description. File format, metadata, lifecycle, application-specific necessity, and the rest of the package were not checked. A filename change cannot repair wrong placement in a publishing system.

For the ambiguous labeling row, ask the document owner for content type, approval/status, submission purpose, and intended version. Do not silently select the most familiar labeling destination. For the naming row, v4.0's explicit entry resolves the lookup only after v4.0 scope is established; it does not establish a v3.2.2 destination.

Record the placement decision before handoff

For each submitted document, retain: authority; eCTD version; application/submission context; document purpose and status; selected heading; source revision/page; technical mapping; reviewer; unresolved question and owner. This is a practical review record, not an additional FDA form.

An example is: “FDA; v3.2.2; initial IND; general investigational plan; 1.20; hierarchy v2.3.5 printed page 4; technical encoding awaiting publisher review.” The correct lookup is recorded without pretending the unchecked encoding has passed.

Reconcile the published navigation and metadata with that record, then use the submission readiness checklist for the wider handoff. Keep FDA's v3.2.2 standards or the corresponding v4.0 resources with the release evidence.

If evaluating Assyro's eCTD authoring and validation, confirm the exact application and checks in scope: FDA v4.0 is supported, while v3.2.2 is not currently supported. Ask which placement and metadata checks can be demonstrated against your sample; this reference does not claim automated detection of every error above.