TRUNCATION (WILDCARDS)

Truncation symbols, sometimes called "wildcards", are very useful in searching electronic databases. A truncation symbol represents or replaces any symbol or symbols, including a space. There is not yet a standard truncation symbol, so you need to know the appropriate symbol used by a particular vendor's search engine. Keep in mind that a particular database such as Medline or GeoRef or Agricola may be available from a number of vendors such as SilverPlatter or DIALOG. Here are some of the Truncation Symbols used by systems available at NDSU:

PALS: #
SPIRS: *
FIRSTSEARCH: + (This is not a true truncation symbol. It can only be used to retrieve both singular and plural forms of a word)
DIALOG: ?

Appropriate use of truncation symbols will greatly enhance your literature search. Inappropriate use will result in retrieving a lot of irrelevant material. For example, using PALS, "rock#" will retrieve material containing the words "rock" and "rocks", but it will also return a lot of irrelevant material containing such terms as "rocker", "rocking", "rocket", "rockets", etc. Most search engines will allow truncation at the end of a "root word" such as "structur#", and many will allow truncation within a word, such as wom#n. Most will NOT allow truncation at the beginning of a word.

BOOLEAN OPERATORS

Knowing how to use Boolean Operators will maximize the effectiveness and accuracy of your search. There are three commonly used Boolean Operators: AND, OR, and NOT. Illustration

KEYWORD	DESCRIPTION
AND	Searches for articles containing BOTH the first and second word Example: Volcano# AND Italy
OR	Searches for articles containing EITHER the first or second word Example: maize OR corn
NOT	Searches for articles containing the first word BUT NOT containing the second word. This helps to eliminate unwanted material. Example: depression NOT adult

The SPIRS group of databases can be searched using all three of the Boolean Operators. All three can also be used with DIALOG. For Boolean searching with FirstSearch, use the Advanced option which provides a form. PALS assumes an AND between words. An example of a simple way to use both AND and Or in the Classic PALS system is to type "maize or corn" and hit return. Then, at the prompt, type "and dakota". You will retrieve records containing either "maize" or "corn" or both, but the word "dakota" must also be present. For more complex searches in PALS pick up a copy of "Online Catalog Commands" at the Library Reference Desk.

NESTING

Some search systems such as SPIRS and DIALOG provide the ability for very sophistocated searches. Search command "strings" can be "nested" within parentheses, and executed in steps. This process works something like a complex mathematical formula. For example, type: (soil* or groundwater) and (pesticide* or pollut*) and agricult* The SPIRS search engine will find all records containing the words "soil" or "soils" or "groundwater". It will also find all records containing the words "pesticide" or "pesticides" or "pollution" or "polluted" or "polluting". Then it will find all records containing the words "agriculture" or "agriculural". Finally, the search engine will return all records having at least one word from each of the three groups.

ADJACENCY OR PROXIMITY

Search engines have different ways of dealing with the nearness of words to each other, which is known as adjacency or proximity. The PALS systems does not have an adjacency feature. The PALS search engine looks for the given words any place in the record. The SPIRS system treats words as a phrase unless they are separated by Boolean Operators. The FirstSearch system assumes a Boolean AND between words. To connect words of a phrase insert W (with) or N (near): "North w Dakota" will retrieve only "North Dakota". "North n Dakota" will retrieve "North Dakota" or "Dakota North". Type a number (1-25) after W or N to specify the number of words allowable between terms in a phrase. The DIALOG system also uses proximity or adjacency connectors. In this system the proximity connector is enclosed in parentheses with no spaces. Type "North(w)Dakota" to look for North Dakota, or "gone(2w)wind" for "Gone with the Wind".

SPECIAL FEATURES

Each search system has unique special features. See the various Library "handouts" on the Library Web pages, or the "help" features of the various search systems. A Reference or Subject Librarian will be glad to help you.