In a Boolean sense, OR really grabs all of the items and puts them into a set. In the first case, we would be left without dessert because the NOT completely eliminates the set that is ANDed together when one of the terms satisfies it. It throws out the bowl containing the cake AND the ice cream. The NOT command must be used with caution in online searching since it could eliminate some documents that are of interest if they also happen to discuss aspects of a topic that are not of interest. There are more specific variants of the AND command that can be used to define the spatial relationships of search terms.
Truncation can occur at the left end or the right end of a word stem or within the word.
STN now allows all three types of truncation in the CA File Basic Index. The limit of terms that can be gathered in a set by truncation is 30,000 stems. For left truncation the search term must have at least four characters. Logging On and Logging Off One way to gain access to the STN International system is via telephone lines and a modem. All commercial systems that charge for online searching of their databases require a loginid and a password.