The XSL Boolean Operators
By definition, Boolean operators are operators that accept one or more values of true or false and return a single value of either true or false. The three primary Boolean operators in any language are AND, OR, and NOT. While you may be aware of additional Boolean operators in other languages, it's well known that these three can be used to create all possible Boolean expressions. Therefore, the presence of other operators adds no additional power to the language.
Since AND, OR, and NOT can appear in normal use, there needs to be something to differentiate them from English syntax. The notation for the Boolean operators relies on the dollar sign ($) character to differentiate the operators from the corresponding English ...
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