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Dialog Command Language Search Basics

A search using Dialog Command Language can be as simple as typing a few words of text, or it can incorporate an array of search features and commands that can enhance both the search process and the final search results. Every search involves an interaction between you and the search engine — a “dialog.” This Basics section describes how to enter commands, put searches together using operators, display output and use special techniques for numeric and range searching.

Accessing Dialog

All Dialog Command Language interfaces are accessible via the Internet using TCP/IP protocols, most commonly using:

• A Web browser. Internet Explorer 5.X or higher or Netscape Navigator 4.7 or higher are recommended.
• TELNET (text-based communication over the Internet).
• Communications software that supports TCP/IP, such as DialogLink 5.

Internet access is available at the desktop in most businesses and academic institutions. Internet Service Providers (ISP) also provide Internet access for a fee by means of a telephone dial-up connection, DSL, broadband cable, or wireless service. In addition to Internet access, you will also need a valid user account for Dialog. Each account is assigned a User ID and password that are required in order to log on to the service. Institutions also may opt for automatic authentication for some Dialog services in lieu of individual User IDs and passwords. Contact your account representative or the Dialog Knowledge Center for more information. Dialog interfaces that support Command Language are listed below.

Entering Commands

After signing on, you will see a system prompt: a question mark ?. This signals that the system is ready to accept a command. [Note: In DialogWeb—Command the question mark (?) system prompt does not display.] To instruct the system what to do, type a command in the prompt line (DialogClassic) or input box (DialogClassic Web, DialogLink 5, DialogWeb—Command). Press the <ENTER> key to send the command.

Most commands are followed by some additional data before <ENTER> is pressed. For example, the BEGIN command is followed by a file number(s), a category name(s), or a combination of both. Most commands can be abbreviated. In general, the format for entering a command is:

COMMAND   SPACE   DATA   <ENTER>

You can enter up to 2,000 characters (including commands, punctuation, and spaces) following any system prompt before pressing <ENTER>.

Truncation

Truncation is used to permit variations in word length or spelling of search terms with the SELECT command (abbreviated “S”).

Note: Prefix truncation is only available in TRADEMARKSCAN® databases in the TR= field.

Operators

Logical Operators

Three kinds of logical relationships can be defined in SELECT statements using Dialog Command Language: OR, AND, and NOT.

• OR logic is specified using the word OR, truncation, or range searching.
• AND logic is specified using the word AND or a proximity operator.
• NOT logic is specified using the word NOT or a NOT proximity operator.

Symbols may be used in place of the word:

OR +

AND *

Proximity Operators

Proximity operators are used to control how close terms are to appear to one another in documents retrieved.

• (W) Requests that terms be adjacent to each other and in the order specified. Can also be used to retrieve identical terms.

• (N) Requests that terms be adjacent but in any order. Can also be used to retrieve identical terms.

• (S) Requests that terms be in the same subfield as defined by the database. In full-text files, requests that terms be in the same paragraph.

• (F) Requests that terms be in the same field, as defined by the database.

• (L) Requests that terms be in the same descriptor unit as defined by the database, such as ASTHMA — DIAGNOSIS , a pre-coordinated or “heading-subheading” subject descriptor.

• (T) Used for chemical name searching in selected files; used to retrieve one part of a chemical name with another part.

NOT may be combined with a proximity operator, e.g.,

    SELECT ECONOMIC(NOT W)RECOVERY 
    SELECT BULIMIA(NOT L)PATHOLOGY 

Order of Precedence

You can use any of the logical operators (OR, AND, and NOT) and any of the proximity operators in the same SELECT statement. The system first processes any proximity operators that it finds in a SELECT statement. The next operator to be processed is NOT, followed by AND, and finally OR. To alter this order, place parentheses around the group of terms and operators that must be processed first. Parentheses are most often used to specify that an OR combination be processed before an AND combination. You may use more than one level of parentheses in a SELECT statement; the innermost group is processed first.

Order of Processing

Parentheses

proximity operators

(T W N L S F)

NOT

AND

OR

cont'd 

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