Magazine article Online

BRS/LINKs to the Future: Online Hypertext Is Born

Magazine article Online

BRS/LINKs to the Future: Online Hypertext Is Born

Article excerpt

The advent of hypertext brings the future, with its vision of the electronic library, one step closer [1]. The ability to use hypertext to bring a variety of information sources to the fingertips of the searcher is limited only by imagination, manpower, and money.

Hypertext has already been used to create electronic textbooks and CDROM products but what about its use with existing online databases containing millions of documents?

Writing in ONLINE in January 1989, McClelland points out that the basic problem with applying hypertext to large online databases is the massive task of identifying the potential links and then establishing a code in the database which would allow them to be accessed easily [2]. The manpower to accomplish such a task would be staggering and the costs prohibitive. However, there are complementary databases where items correspond so closely that it is possible to easily match segments, such as a bibliographic citation to its full-text article or abstract in another database.

In May 1989, BRS Information Technologies, a division of Maxwell Online, announced the new BRS/ LINK feature, a hypertext function which connects related databases and permits automated cross-database searching. The first LINK application relates the citation in a bibliographic database to its full-text article in a second database. After identifying a desired citation, the searcher can retrieve the full text of the article from a "linked" database. The new feature eliminates the need to re-execute a search strategy in the second database in order to find the corresponding full-text article. Currently the LINK FULL TEXT or LINK FT function links only from MEDLINE (MESH or MESZ), Health Planning and Administration (HLTH) and MEDLINE References on Aids (MRAI) databases to the Comprehensive Core Medical Library (CCML), a full-text database of medical journals and books.

HERE'S HOW IT WORKS

First, run a search strategy in one of the above databases. Peruse the titles of articles and identify desired items. Use the LINK 1 FT to link citation #1 to its full-text article in CCML. If the link is successful, the full text from CCML will be printed. If it is unsuccessful, the system will respond with a message stating that the full text is not available. Only one item at a time can be linked, and the link must be executed at a print prompt L:).

EASING THE WAY

There are ways to increase the chances of finding linkable citations. The FT field was recently added to the MEDLINE files and contains a statement that the journal is available in CCML beginning with a specific issue and date. After completing a search on MEDLINE, use ..L/FT=Y command to limit the retrieval to journal titles that are in CCML. Print the Ti, SO, FT fields and compare the journal issue number with those covered in CCML. Each journal's coverage dates in CCML and MEDLINE do not correspond exactly. The majority of the CCML journals go back only to the mid-1980s while MEDLINE coverage goes back to 1966. The BRS News Document 34 lists the precise time span for each of the more than 70 journals that are part of CCML. Occasionally the most recent issue is not in the CCML database, even when its citation can be found on the MEDLINE database. One problem to overcome when using LINK from the BRS command-driven access is that LINK must be executed at a print prompt L:). Here is a short cut that can be used to trick the system into giving a print prompt. Review the entire list of citations before attempting a link, issue the print command with a document number higher than actually in the search set. After printing the list, BRS will respond with the error message DOCUMENT NUMBER WAS TOO HIGH which ends with a print prompt. You can then enter a link 1 ft command where the 1 means document #1 in the list Figure 1).

LINK can also be part of a stacked Print command such as ..p 3 bibl, ft/1-5/link 2 ft. …

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