A search expression consists of one or more terms associated with one or more logic operators. There are two kinds of search terms: exact terms or roots of exact terms with a cutting off. The operator of the cutting off is $. For example the search "metr$" retrieves all the terms wich start with the root "metr" as metrica, metro, metronomo.

Boolean logic operators

+	OR	A + B	A or B or both
*	AND	A * B	At the same time A and B
^	NOT	A ^ B	Only A but not B

Proximity operators

A proximity operator determines the closeness of terms within a source document. NEAR is a restrictive AND wich retrieve the records with the two terms

(G)	A (G) B	In the same field
(F)	A (F) B	In the same circumstance
.	A . B	Distant between them no more than n* words
$	A $ B	Distant between them exactly n* words
* n is the number of points or dollars less one

Note that the operators . and $ must be preceded and followed by a blank.

Field operator

By default ISIS searches in all indexed fields. The field operator restrict the search at one or more fields from wich the term was extracted. The syntax is term/(i1,i2,i3,in) (for example: history/(11,62)) where:

• term = search term
• /(...) = defining operator
• i1,in = numbered tag of the field

Search expression syntax

It is possible to combine two or more terms with the search operators by the utilization of the round brackets and it is also possible to modify the priority order of the exectution of the operators as below:

(upper) $ and .; (F); (G); * and ^; + (lower)

For example: ((A + B) * C + (D + E) * F) ^ G