     |
| boolean boolean( object) | Returns the boolean representation of the object argument. |
| boolean not( boolean) | Returns a boolean with the opposite value of its argument. |
| boolean true() | Returns a boolean with the value of true. |
| boolean false() | Returns a boolean with the value of false. |
| boolean lang( string) | Returns true if the language of the context node is the same as the languag specified by the argument. |