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October 25, 2006 [posted]

MEDLINE®/PubMed® End-of-Year Activities

the National Library of Medicine® (NLM®) is currently involved in MEDLINE year-end processing activities. These include changing the Medical Subject Headings (MeSH®) on existing MEDLINE citations to conform with the 2007 version of MeSH, and other global changes such as those to Supplementary Concept Substance Names. The majority of MEDLINE data changes will be covered in forthcoming NLM Technical Bulletin articles, to be titled MEDLINE Data Changes - 2007 and What's New for 2007 MeSH. A new Web page, National Library of Medicine (NLM) Annual MEDLINE/PubMed Year-End Processing Activities, provides background and examples about the typical changes that take place for MEDLINE citations during year-end processing.

Indexed Citations

On November 15, 2006, NLM expects to temporarily halt the addition of fully-indexed MEDLINE citations to PubMed. NLM indexing staff will continue to index citations, but these completed records will be held and not added to PubMed until the normal update schedule resumes.

According to the normal MEDLINE/PubMed update schedule, MEDLINE citations are released and revised Monday through Friday, and these citations are then available to MEDLINE licensees and PubMed users Tuesday through Saturday. During end-of-year activities, NLM's schedule for adding indexed citations to MEDLINE and PubMed is temporarily interrupted. Once the end-of-year activities are complete (tentatively targeted for mid-December 2006), the normal MEDLINE/PubMed update schedule will resume, and PubMed will use 2007 vocabulary in the MeSH translation tables and MeSH database, as well as in the citation data.

In-Process Citations

During end-of-year activities, "in-process" citations will continue to be added to PubMed. As a result, the number of PubMed records labeled [PubMed - in process] will temporarily increase. These citations do not have MeSH terms, but they have undergone issue level and subsequent citation level quality control reviews.


A search limiting terms to fields affected by indexing (e.g., telemedicine [mh] AND clinical trial [pt]) does not retrieve in-process or publisher-supplied records (see data added, changed, or supplemented during indexing). Therefore, during end-of-year activities when we are not adding completed, indexed citations to MEDLINE/PubMed, such searches - including those stored in My NCBI and retrieved through RSS feed stored searches - may not retrieve new records for some weeks. To retrieve new, in-process records during this time, you should use searches that do not limit to affected fields (e.g., telemedicine clinical trial). Note that the search terms are not tagged in this example. By mid-December, the in-process citations that are within the scope of MEDLINE and that have been indexed since November 15, 2006 will be replaced as indexed citations with 2007 MeSH terms, Publication Types, etc. Searches, including My NCBI Stored Searches, containing tagged search terms will then retrieve all applicable MEDLINE records.

Corrections on Hold

Also as of November 15, 2006, corrections to completed MEDLINE citations (e.g., to correct an author name misspelling) will not be released to MEDLINE. NLM staff will continue to correct completed citations and these will replace the incorrect citations in MEDLINE when the normal update schedule resumes.

Data (with search tags) added to MEDLINE records during indexing:

EC/RN Number [rn]

Grant Number [gr]
Some grant numbers are added during indexing, but the majority are present while the citation is "in process."

MeSH Terms [mh]
Includes age groups; Humans/Animals; Male/Female

MeSH Major Topic [majr]

Publication Type [pt]
Some publication types are present on in process records but many are added during indexing.

Subheadings [sh]

Subset [sb]
Citation status values change from "In Process" to "MEDLINE" once MeSH indexing has been completed

Substance Name [nm]

English [la] is not on this list. Limiting to English language will retrieve in process records.

By Sara Tybaert
MEDLARS Management Section

Tybaert S. MEDLINE®/PubMed® End-of-Year Activities. NLM Tech Bull. 2006 Sep-Oct;(352):e9.

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