Support : Dialog Search Aids : Descriptors and Online Thesaurus in Dialog File 8

Descriptors and Online Thesaurus
in Dialog File 8, Ei Compendex®
SubheadingOrTagline

19 September 2000

Descriptors are single-word or multiple-word main headings and/or subheadings assigned from the controlled vocabulary. Each record is assigned one major descriptor and up to five additional descriptors. Descriptors are comprised of a main heading, and if appropriate, a subheading, to reflect the most important aspect of the main heading concept. Main headings and subheadings are indexed separately and treated as individual descriptors. Major descriptors appear as the first descriptor in the record, and both the main and subheading parts are asterisked to designate them as major descriptors. Use the /DE* or /DF* suffix to limit the search to major descriptors. However, restricting a search to only major descriptors may result in the loss of relevant records.

The following record illustrates the Descriptor field:

DIALOG(R)File   8:(c) 2000 Engineering Info. Inc. 
All rts. reserv.
02647019
  Title:  THOUGHTS  ON  RECOVERY  AND  ENVIRONMENTAL 
IMPLICATIONS OF TRACE ELEMENTS IN SOUTH AFRICAN COAL 
COMBUSTION RESIDUES.
  Conference  Title:  Ash - A Valuable Resource, 
Papers. v 3, Environmental Aspects, Special Products, 
Mineral Beneficiation.
  Publication Year: 1987
  Descriptors: *COAL ASH--*Environmental Impact; COAL 
COMBUSTION--Environmental Impact
  Identifiers: TRACE ELEMENT RECOVERY; ASH COMPOSITION; 
ELECTROSTATIC PRECIPITATION
  Classification Codes:
  521  (Combustion & Fuels); 524  (Solid Fuels); 454  
(Environmental Engineering)
  52  (FUEL TECHNOLOGY); 45  (POLLUTION & SANITARY 
ENGINEERING)

Some terms are used both as main headings and as subheadings, e.g.,

ABLATION	        SPACE SHUTTLES--Reliability
PLASTICS--Ablation	RELIABILITY--Optimization

Descriptors may appear as a single word, phrase, inverted phrase:

Single word	e.g., CLAY
Phrase	e.g., CLAY DEPOSITS
Inverted phrase	e.g., CLOCKS, ATOMIC

Descriptors may be searched as single words, using proximity operators, or as multiple-word phrases with the /DE suffix, e.g.,

SELECT ELECTRIC(W)LAMPS/DE
S1    3111	ELECTRIC(W)LAMPS/DE
SELECT ELECTRIC LAMPS/DE
S2    1554    ELECTRIC LAMPS/DE

Note that the results of the two previous statements show that retrieval is higher when proximity operators are used. SELECT ELECTRIC LAMPS/DE retrieves only that complete phrase, whereas SELECT ELECTRIC (W)LAMPS/DE retrieves such descriptors as ELECTRIC LAMPS, FLUORESCENT and ELECTRIC LAMPS, METAL VAPOR as well as ELECTRIC LAMPS.

Since all multiple-word descriptors are also indexed under each individual word of the phrase, it can be useful to differentiate between single-word descriptors and the same single words extracted from multiple-word descriptors. For example, SELECT CLAY/DE retrieves such descriptors as CLAY; CLAY DEPOSITS; CLAY PRODUCTS; and PIPE, CLAY. Similarly, SELECT CLAY/DE* retrieves these terms if they have been asterisked as major descriptors. However, SELECT CLAY/DF retrieves only the single-word descriptor CLAY, and SELECT CLAY/DF* retrieves the single-word descriptor only if it has been asterisked as a major descriptor.

Descriptors may include hyphens, commas, or other punctuation. Retain exact spacing and punctuation when selecting a descriptor as a complete phrase, e.g., SELECT X-RAY APPARATUS/DE. If a descriptor includes a slash (/) or some other character that cannot be selected directly, the descriptor phrase must be enclosed in single or double quotation marks, e.g., SELECT "VOICE/DATA" INTEGRATED SERVICES/DE.

Use the (W) operator to replace all punctuation when selecting descriptors using prox-imity operators, e.g., SELECT X(W)RAY(W)APPARATUS/DE.

Descriptors are arranged in heading--subheading pairs to allow accurate retrieval. Use the (L) operator to retrieve a main heading--subheading pair, e.g.,

?SELECT CRYOGENICS(L)SPACE APPLICATIONS
     S3  126    CRYOGENICS(L)SPACE APPLICATIONS
?TYPE S3/6,DE
3/6,DE/1
DIALOG(R)File   8:(c) 2000 Engineering Info. Inc.
All rts. reserv.
03459920
  Title:  Recent developments in Stirling and pulse
tube coolers for spacecraft applications.
  Conference  Title: 1991 International Geoscience
and Remote Sensing Symposium - IGARSS'91
  Publication Year: 1991
  Descriptors: CRYOGENICS --*Space Applications ;
INSTRUMENTS--Cooling; SPACECRAFT--Equipment

Note that /DE is not needed in the previous search because the (L) operator automat-ically restricts retrieval to the Descriptor field.

Online Thesaurus. Compendex has a printed and an online thesaurus to verify controlled terms. Use EXPAND command to determine whether a word or phrase is appropriate as a search term. EXPANDing results in an alphabetical listing of the database index roughly beginning at the word or phrase you entered:

EXPAND PROGRAM COMPILERS
Ref   Items   RT  Index-term
E1        9       PROGRAM COMPILATION
E2        4       PROGRAM COMPILER
E3     4945    5 *PROGRAM COMPILERS (January 1993)
E4        1       PROGRAM COMPLETION METHOD
E5        4       PROGRAM COMPLEX
E6        1       PROGRAM COMPLEX RADIUS
”

Note the RT column. The word or phrase may have related terms--words or phrases that may represent the same con-cept, but may not be alphabetically close to the term you entered. To view the related terms EXPAND again, referencing the appropriate E number:

EXPAND E3
Ref   Items Type  RT  Index-term
R1     4945        5 *PROGRAM COMPILERS (January 1993)
R2        0   F    2  COMPILERS (PROGRAM)
R3        0   F   11  COMPUTER OPERATING SYSTEMS--PROGRAM 
R4     3923   B   10  PROGRAM PROCESSORS (January 1993)
R5      736   R    9  COMPUTATIONAL GRAMMARS (January 1993
R6      642   R    5  PROGRAM DIAGNOSTICS (January 1993)

At any point, you can select appropriate reference numbers to create sets of the terms. EXPANDing on a term within parentheses is a way to directly access the Related Terms display (rather than expanding twice):

EXPAND (PROGRAM COMPILERS)
Ref   Items Type  RT  Index-term
R1     4945        5 *PROGRAM COMPILERS (January 1993)
R2        0   F    2  COMPILERS (PROGRAM)
R3        0   F   11  COMPUTER OPERATING SYSTEMS--PROGRAM 
R4     3923   B   10  PROGRAM PROCESSORS (January 1993)
R5      736   R    9  COMPUTATIONAL GRAMMARS (January 1993
R6      642   R    5  PROGRAM DIAGNOSTICS (January 1993)

Within most R-numbered lists, a column labelled "Type" shows the hierarchical relationships among the terms in the list. Typical entries in this column include:

F	Use for
U	Use
N	Narrower term
B	Broader term
R	Related term

Using Explode. The Explode feature is designed to take advantage of the hierar-chical organization of online thesaurus. It speeds the retrieval by automatically selecting a term plus narrower related terms. To Explode a term, SELECT the term with an ending exclamation mark:

SELECT VEHICLES!
S4   28028  VEHICLES!
TYPE S4/DE
4/DE/1
DIALOG(R)File   8:(c) 2000 Engineering Info. Inc. 
All rts. reserv.
  Descriptors: Piezoelectric materials; Space 
applications; Spacecraft ; Finite element method; 
Modal analysis
 4/DE/2
DIALOG(R)File   8:(c) 2000 Engineering Info. Inc. 
All rts. reserv.
  Descriptors: Steel; Bicycles; Light weight vehicles ;
Weight control