University of Maryland College of Information Studies
Command Language Comparison:
Dialog Classic, Gale, Google, and MdUSA
Christina K. Pikas
LBSC 750
Due: December 6, 2001
Introduction
The purpose of this paper is to examine the differences between the command languages
used by different database vendors. The database vendors were selected to provide a broad
comparison in command languages and also because these are databases that the author
frequently uses. The following vendors (and versions) were selected:
The Dialog Corporation. “Dialog Classic Version 2.0.” 2001.
http://www.dialogclassic.com, accessed December 2, 2001.
Gale Group, Inc. “Gale Info Trac Web.” 2000.
http://infotrac.galegroup.com/itweb/prge_main, accessed December 2, 2001.
“Google.” 2001. http://www.google.com/, accessed December 2, 2001.
“MdUSA.” http://mdusa.lib.umd.edu, accessed December 2, 2001.
Although TheThomson Corporation owns both Dialog and Gale Group they are
dramatically different. Only a small subset of the databases available through Dialog Classic is
available through Info Trac Web. Dialog Classic bills by time and by output, while Info Trac
Web is site-licensed for unlimited searches.
MdUSA is the University of Maryland system’s shared portal for searching the majority
of the databases licensed by the schools. It offers the ability to search databases from multiple
vendors at the same time, the Jointly Administered Knowledge Environment (JAKE) tool which
allows the user to determine which databases index which journals, and allows for remote access
to the databases. Some of the databases open in the vendor’s portal, but the majority use the
MdUSA interface. MdUSA is only available to registered students, staff, and faculty of the
University of Maryland.
Finally, Google (www.google.com) is a popular Internet search engine. The command
language and advanced search options are discussed below.
Expectations
There are several things that all useful command languages will have. These minimum
expectations allow users to efficiently find records matching the information need and to move
quickly from program to program. The first of these expectations is the ability to use Boolean
logical operators including AND, OR, and NOT. The second is the ability to access indexes
directly. In other words, full text searching using a keyword can be an option, but should not be
the only option. Preferably, access should be given to author, title, publication date, and source
(i.e., journal name) indexes as a minimum. Stop words should be specified in the help screens.
Phrase searching and nesting functions should be allowed. Truncation and proximity searching
are also very desirable.
In addition to the above functions, the command language should make sense and be easy
to learn. Many vendors have flattened the learning curve by adding drop down boxes so that
average users can avoid learning the advanced language idiosyncrasies. Advanced users should
still be able to use the commands directly.
Internet search engines should also have the features listed above. Additionally, file type
searching and image or media searching is desirable. The ability to adjust set size is an
important feature for speed and ease of use.
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Differentiating Features
The various features of the four command languages are compared in a table located in
the appendix.
Dialog Classic
A user cannot use Dialog Classic unless she is well versed in the advanced command
language. Online help screens are available but it is not clear if the system continues to rack up
dial units while the help screens are open.
A nice feature Dialog has that was not found in the other command languages was the
ability to remove duplicates within the search results.
Once the user is trained in the command language and features, Dialog Classic is very
powerful. It has all of the required features and also has special output formats to easily export
the data for labels or to spreadsheet or citation software. Unfortunately, the data is not formatted
attractively for printing as in the case of Info Trac web or MdUSA.
Gale Info Trac Web
A nice feature of the command language is the ability to browse indexes. This is similar
to the expand command in Dialog. Also, the thesaurus is available to search using the “subject
guide” feature. The cross-references, broader and narrower terms are hyperlinked with the
number of articles with each term listed. Also, a large quantity of the articles has permanent
URLs so that they can be bookmarked and retrieved later.
The relevance search feature includes automatic stemming and ranking functions. For all
searches the keyword search can be over the full record or limited to just the title, citation, and
abstract, the equivalent of the basic index in Dialog Classic.
Google
One major differentiating feature of Google is that it does not offer truncation or word
stemming. The basic help page states that this feature is not offered to increase search accuracy.
Google will also return pages that do not have the words that are combined with AND in the
search. This way, the user will always get results. The advanced user can use the + symbol to
require any word. Stop words are mentioned in the help screens but no list of words is offered.
On the other hand, Google offers quite a few unique and unexpected features. First, it
allows the user to specify how many occurrences in the page the word must have. Second, it has
a spell checker for your search. It is not exactly clear what some of the functions in Google do.
For example, how are related pages determined? Are they pages that are linked? If so, how is
that different from the link: command?
Beta or testing features of Google will enhance its use. The image search engine is
already very useful but the translation feature could use some work. A German website on
turbochargers was completely nonsensical when run through the translator.
MdUSA
The first major differentiating feature is that MdUSA allows the user to search multiple
databases at the same time. This is also available through Dialog Classic, but is not available
through Info Trac Web. By creating a Topic, the user can specify a group of individual
databases besides the pre-selected groups to search.
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Another important feature of MdUSA is the ownership index. When the full record is
viewed, area institutions owning the journal or monograph are listed and the University of
Maryland System Libraries owning the item are listed.
From the advanced search page, the records can be automatically sorted. Also set size
and record format can be selected. Records including full text can be formatted for printing or emailed to a given address.
The help pages for MdUSA do not provide a list of stop words but are otherwise helpful.
Conclusion
Overall the four command languages performed as expected. This is surprising, because
some of the expected features were not discovered until the documentation was thoroughly
examined. It is also surprising that Google does not offer truncation to improve accuracy.
Perhaps the designers should also eliminate OR?
After doing this research the author feels comfortable recommending these command
languages for any search. Dialog Classic would not be the first choice if Info Trac Web or
MdUSA are offered due to system pricing. Also the time the information professional would
have to allot for packaging the search would be much greater for Dialog than the other two.
Google remains the premier Internet search engine. Many of its features are not equaled
in other engines; however, most of the features are rarely used.
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Appendix: Comparison Chart
Feature
Indexes
(can vary
with
database)
Dialog
Author AU=
Company CO=
Corporate Source
CS=
Document Type
DT=
Journal JN=
Language LN=
Publication Date
PD=
Publication Year
PY=
Sales SA=
Update UD=
Info Trac
Abstract ab
Author au
Keyword ke
Source so
Subject su
Text Word tx
Title ti
(Can browse
indexes)
MdUSA
Abstract
Author
Keyword
Subject headings
Subject words
Title
Year of
publication
(Can browse
indexes.)
Wildcards/
Truncation
? any number of
characters
? ? exactly one
character
?? number of
characters
And
Or
Not
( ) to nest
* any number of
characters
? exactly one
character
! one or no
characters
And
Or
Not
( ) to nest
+ must contain
- must not contain
Wn within
Nn near
? any number of
characters
Boolean
Proximity
Range
Quotes
(nW) within
(nN) near
(S) subfield
(L) linked
(F) same field
(T) same term
: between
> greater than
< less than
And
Or
Not
( ) to nest
Google
Allintitle
Allinurl
Cache
Date
Domains
Format
Intitle
Inurl
Language
Link
Occurrences
Related
Safesearch
Spell
Stocks
Site
Not offered
And (understood)
Or
+ must contain
- must not contain
Wn within
Nn near
Note: must have
number
Since, after, gt, >
more recently
Ge on or after
Before, lt, < earlier
than
Le on or before
To, - between
Yes
Yes
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Bibliography
The Dialog Corporation. Dialog Pocket Guide. Cary, North Carolina: 2001.
Gale Group. “Help on Help Index.”
http://web1.infotrac.galegroup.com/itw/infomark/15/111/18362646w1/3!help_Help_Index,
accessed November 7, 2001.
_____. “Info Trac Web Fact Sheet.” http://www.galegroup.com/pdf/facts/itweb.pdf, accessed
November 25, 2001
Google. “Advanced Google Search Operators.” http://www.google.com/help/operators.html,
accessed November 7, 2001.
Google. “Google Help.” http://www.google.com/help/refinesearch.html, accessed November 7,
2001.
MdUSA. “Searching.” http://mdusa.lib.umd.edu/html/help.html, accessed November 7, 2001.
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