LM is adding data to LocatorPlus records to support an expanded MEDLINE. MEDLINE is expanding to include unique journal citations from AIDSLINE, HISTLINE, SPACELINE, BIOETHICSLINE and POPLINE. NLM plans to add these citation subsets to MEDLINE later this year.

The selection of journals and articles indexed varies with each of these subsets of citations. Article selection was and is under the direction of the cooperating partner who creates and indexes the data. Citations in some subsets were selected from a list of core journals that were reviewed regularly. Others reflect article selection from the universe of published literature and were not limited to a specified list of source journals. It is possible that there may be only one, or very few, citations from some journals in the expanded MEDLINE.

The new Citation Subset values to be introduced in LocatorPlus records and expanded MEDLINE citations during 2001 are:

The additions to LocatorPlus must occur in advance of converting the citation data to PubMed. This is because there must be a record in LocatorPlus for the host journal of every citation in MEDLINE. Therefore, work is underway to create or update thousands of LocatorPlus records to indicate MEDLINE indexing for the citation subsets. As this work must be completed before any citations are added to MEDLINE, many journal records in LocatorPlus already contain indexing status information but do not yet have citations in PubMed.

This article provides instructions for locating MEDLINE citation sources in LocatorPlus and explanations of indexing status information in LocatorPlus records.

How to locate the source of a MEDLINE citation

• Every MEDLINE citation in PubMed contains the Journal IDentification number, or JID, of the source journal. Display the PubMed record in MEDLINE format to see the JID.
• Every journal that is cited in MEDLINE is found in the NLM catalog, LocatorPlus, available at: http://locatorplus.gov .
• To locate the record for the source journal, search for the JID in LocatorPlus, using the Keyword Anywhere search. In the LocatorPlus record, the JID is found in the NLM Unique ID field.

How indexing status is indicated in LocatorPlus
LocatorPlus includes Abstract/Indexing and, for some unique journals, Citation Subset information in the source journal record. Abstract/Indexing information describes where the journal is indexed (e.g., Index Medicus, MEDLINE) and the type of coverage. For many journals indexed in MEDLINE, coverage is complete: the journal is indexed "cover-to-cover." For some others (e.g., Nature, Science) coverage isselective: the journal covers a wide range of subjects but only articles that are in scope for MEDLINE are selected for indexing. The Citation Subset information identifies the topical area for which the journal is indexed.

Abstract/Indexing and Citation Subset information are displayed in the Details and MARC views of LocatorPlus records.

• Abstract/Indexing information
  In the LocatorPlus Details view, a note identifies journals indexed in MEDLINE. This displays as:
  
  Indexed in: MEDLINE
  
  In the LocatorPlus MARC view, the 510 field contains abstracting and indexing information. A numeric MARC code indicates coverage and subfield a contains the value "MEDLINE." This displays as:
  
  

  510 1_ |a MEDLINE	[1 indicates that coverage is complete]
  510 2_ |a MEDLINE	[2 indicates that coverage is selective]
  510 0_ |a MEDLINE	[0 indicates that coverage is unknown]

  The 510 subfield b contains the issue and date when indexing started or stopped. For example, the MARC view of Journal of Clinical Oncology contains:

  

  The Details view of Journal of Clinical Oncology displays this information as:

  

  For many journals cited in the expanded MEDLINE, the coverage is unknown and the start and/or stop date for indexing coverage is not specified. The note "Date range of indexed citations unspecified" indicates this coverage status. For example, the MARC view of Journal of Atmospheric Chemistry contains:

  

  In the Details view, this displays as:

  

• Citation Subset Information
  

  Citation Subset values are found in the 911 field of the MARC view as shown here:

  

Remember: We are adding Abstract/Indexing data and Citation Subset values to LocatorPlus records in advance of converting the citation data to PubMed. Even if a journal's LocatorPlus record is tagged as MEDLINE, the citations for that journal title may not be in PubMed yet, especially if the 510 MEDLINE / Indexed in: note contains "Date range of indexed citations unspecified" and the 911 field contains one of the new subset values listed above. As of March 2001, only the HealthSTAR unique journal citations are in PubMed.

Internet Grateful Med access to the legacy ELHILL databases will be phased out as citations become available in PubMed. For more information see the January-February 2001 NLM Technical Bulletin at: www.nlm.nih.gov/pubs/techbull/jf01/jf01_igm_phaseout.html.

For information on journal citation subsets already searchable in PubMed, see the January-February 2001 NLM Technical Bulletin article at: http://www.nlm.nih.gov/pubs/techbull/jf01/jf01_pubmed_2001.html.

By Andrea Demsey and Jan Willis
MEDLARS Management Section

Demsey A., Willis J. New Indexing Information in Display of LocatorPlus Records. NLM Tech Bull. 2001 Mar-Apr;(319):e6.