Year-End Processing (YEP)
[This link was removed because it is no longer valid] 1998 NLM Pricing Algorithm Chart
New MEDLINE® Backfile and MEDLINE Backfile Configuration - 1998
During 1997 Year-End Processing, all citations published in 1994 or earlier will be pulled from MEDLINE and placed in the appropriate Backfiles. MEDLINE Backfiles and their years of coverage will change again in 1998 with the introduction of a new Backfile called MED93. The primary dates of coverage for MEDLINE and its Backfiles for 1998 will be as shown in the box to the right:
Reminder to PubMed searchers: PubMed searches MEDLINE, PREMEDLINE® and all Backfiles at one time.
Expansion of Dates in MEDLINE Files for Year 2000
During 1997 Year-End Processing, the following date fields (see Figure 1) in MEDLINE files on ELHILL will be expanded by two-digits to accommodate the new format required for the Year 2000. See Figure 1 below.
Figure 1- List of date fields to be expanded in 1998.
Date of Publication (DP)
The year of publication is already stored and displayed in YYYY format in the first four characters of the DP, which requires no change for the Year 2000. The DP field must be searched with a four-digit value for the year. For example,
DP - 1997 Jan 1
is searchable as:
1997: (DP) or 1997 Jan: (DP) or 1997 Jan 1 (DP)
Expanded date values must be used when ranging. In MEDLINE files, only the Date of Entry (DA) in the above table of date values is rangeable. For example, in 1998 search:
FROM 19971201 TO 19971231 (DA) or GREATER THAN 19971130 (DA)
The Unique Identifier (UI) field, a sequential accession number, will not be changing. While the first two digits in this eight number field are date-related, the field value does not represent an actual date. And since the creation of the PREMEDLINE file, there is no longer a strict correspondence between the first two-digits of a Unique Identifier and the year in which the citation is indexed.
Databases containing MEDLINE-derived records (e.g., AIDSLINE®, HealthSTAR® etc.) will reflect the changes described above. Other files and any fields that will have changed displays and search capabilities will be discussed nearer the time those files are class maintained and show the new format.
PubMed and Year 2000 Formats
PubMed contains a searchable Publication Date [DP] field (remember that PubMed search field qualifiers take square brackets) where the year of publication is searchable only as a four digit number, with or without the month and day values. If you choose MEDLINE report for the display format, the year displays as a four digit number in the Date of Publication (DP) field, exactly as it does in the ELHILL version of MEDLINE. For example,
DP - 1997 Jan 1
is searchable in PubMed as:
1997/01/01 [dp] or 1997/01 [dp] or 1997 [dp]
Note although the month displays as Jan, you must search for it as a two-digit value.
Ranging on Date of Publication in PubMed may take the following formats:
1997/09/01:1997/09/30 [dp] or 1997/09:1997/10 [dp] or 1996/12:1997 [dp] or 1996:1997 [dp]
Stay tuned for more information about how non-searchable date-related fields in PubMed will be displayed.
Internet Grateful Med
Searching by date in Internet Grateful Med (IGM) is unaffected by Year 2000 changes. Users will continue to search by selecting the range of years or the individual year from the Apply Limits section of the IGM search screen. Records will display the year in the four-digit format in any applicable date fields.