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Annual MEDLINE®/PubMed® Year-End Processing (YEP): Impact on Searching During Fall 2012

What is YEP? | Indexed Citations | In Process Citations | Searching | Corrections on Hold | Other Resources

Indexed Citations

On November 14, 2012, 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. Once the end-of-year activities are complete (tentatively targeted for mid-December 2012), the normal MEDLINE/PubMed update schedule will resume, and PubMed will use 2013 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]) does not retrieve in process or publisher-supplied records (see Data added to MEDLINE records 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). 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 14, 2012 will be replaced as indexed citations with 2013 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 14, 2012, 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]
Many publication types are present on in process records but some are added or revised 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.

Other Resources


Important Dates

• November 14, 2012: NLM expects to temporarily halt the addition of fully-indexed MEDLINE citations to PubMed.

• Mid-December 2012: PubMed's MEDLINE citations, translation tables, and the MeSH database will have been updated to reflect 2013 MeSH.

NLM Technical Bulletin Articles

•Articles in the November-December issue that address changes to LocatorPlus and NLM Catalog, which may be different from MEDLINE.

Background information is available in previous NLM Technical Bulletin articles.

Related Articles

Skill Kit: The Effects of Year End Processing (YEP) on Saved Searches or RSS Feeds

Heading Mapped-to Maintenance: for Supplementary Concept Records' Names of Substance

Changes in the Treatment of Chemical Data in MEDLINE Citations

Pharmacologic Action Headings: PubMed