There will be no change to the PubMed DTD for 2027. There are two upcoming changes to PubMed data that will take effect when the 2027 PubMed baseline is published:
- A new allowed value “NotIndexed” will be added for the IndexingMethod attribute of the
element. - PubMed FTP data will be generated using the new process announced in June 2025.
New Allowed IndexingMethod Value
Introduced with the 2017 DTD, IndexingMethod specifies the method used to assign Medical Subject Headings (MeSH) to the citation. The current allowed values include:
- Curated – MeSH indexing is provided algorithmically and a human reviewed (and possibly modified) the algorithm results
- Automated – MeSH indexing is provided algorithmically
- Manual – MeSH indexing is provided by humans
A fourth allowed value, “NotIndexed” will identify citations that are in scope for MEDLINE but do not have abstract text in PubMed and therefore are not indexed with MeSH terms. During Year-End Processing in December 2026, NLM will move these citations from In Process status to MEDLINE status and assign the NotIndexed value. If abstract text is later provided to PubMed, the citation will be indexed, and the status will be updated to the appropriate IndexingMethod allowed value.
PubMed data consumers parsing the IndexingMethod attribute should prepare for this new value.
Updated FTP Data
Starting with the annual baseline release in December 2026, the content of PubMed data distributed via FTP will be generated using the same technology as the PubMed website and E-utilities API; this update means the FTP data will match the PubMed website and API.
Test FTP data generated with the new process is available to help prepare for this transition. Users are encouraged to view the test data and check their workflows. Please share any questions or feedback via the NLM Help Desk. Please note, the test files may differ from the current FTP files due to the data differences described in the June 2025 FTP announcement.
For more information about accessing PubMed data via FTP, please see: Download PubMed Data.
Contact the NLM Help Desk
Please reach out to us if you have questions about these PubMed updates.