ORBIT(ID:4550/orb002)

Query language by SDC
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ORBIT => ELHILL   Enhancement of
References:
  • Lancaster, F. Wilfrid "Evaluation of On-Line Searching in MEDLARS (AIM-TWX) by Biomedical Practitioners" Occasional Papers, Publications Office--215 Armory Building, University of Illinois, Graduate School of Library Science, Champaign, Illinois 61820 view details
  • Hummel, Donald J. "A Comparative Report on an On-Line Retrieval Service Employing Two Distinct Software Systems?" Journal of Chemical Information and Computer Sciences, 15(1) 1975 view details Extract: ELHILL and ORBIT
    The NLM information retrieval system consists of a modification of the SDC ORBIT programs and is identified internally as ELHILL. Extract: Introduction
    NLM on-line experimentation began in late 1967 using
    the ORBIT programs of Systems Development Corporation
    (SDC). The MEDLINE prototype (AIM-TWX) became
    operational in June of 1970. Whole text search experimentation
    on a limited collection of toxicological material
    was begun in mid-1970 using the Mead Data Central system
    since it was specifically designed for whole text search
    and retrieval. The success of this latter experimentation
    led to a competitive procurement for a whole text information
    retrieval system in early 1971. Mead Corporation, Informatics,
    Inc., and Battelle Memorial Institute responded
    to the request for proposal, but surprisingly both SDC and
    Lockheed submitted a no-bid. Evaluation of the proposals
    led to a contract being let to Informatics, Inc., in late
    March of 1971. The system proposed by Informatics was
    the National Aeronautics and Space Administration
    (NASA) version of the STIMS/RECON package with systems
    enhancements to facilitate free text search. During
    the succeeding year, RECON was modified and the TOXLINE
    films were built. The TOXLINE service was publicly
    announced and demonstrated in April of 1972, and service
    instituted in October of that same year. A policy decision
    by the NLM in December of 1973 led to the transfer of
    TOXLINE to the NLM system. Service was offered from
    NLM on April 1, 1974 and discontinued through Informatics
    on April 25, 1974. The NLM information retrieval system
    consists of a modification of the SDC ORBIT programs
    and is identified internally as ELHILL. All comparisons
    drawn in the remainder of this presentation are based
    upon a relatively brief period of one and one-half months
    of operation at NLM and a substantially longer period of
    RECON operation. Extract: ELHILL structure
    The ELHILL inverted file structure is very simple and
    straightforward. All search elements from all fields are contained
    in one alphabetically arranged, heterogenous listing
    in a paired file structure consisting of an index file and a
    postings (linear file record pointers) file. The index file
    contains the term in a 39-character field, a count of the
    number of postings and either the posting when there is
    only one occurrence of the term or an address of the postings
    list for multiple occurrences of the term. All postings
    are four-character records. For textual terms one and only
    one posting is carried in the inverted file for multiple occurrences
    of a term in a single record. The six classes of
    search elements or fields available under ELHILL are: authors,
    language, journal coden, year of primary publication,
    text terms from both the title and abstract fields, and
    Chemical Abstracts Service (CAS) Registry numbers.