OpenSCAD User Manual/Booleans

part of the section on Values, Data Types, and Constants Boolean Values Booleans have two states, true or false. They are the natural result of relational tests ( this==that, this<that, etc. ) and are primarily used as the conditional element in an 'if()' statement or the '? :' ternary operator. More complex boolean expressions may be formed using the logical operators for NOT, AND, and OR ( '!', "&&", "||" respectively). NOTE the NOT EQUALS ( "!=" ) relational operator has the effect of being an XOR (exclusive OR) operator. As variables in OpenSCAD do not have a type the evaluation of an expression being used as the Condition Expression in an if statement may not give a Boolean result. The Non-Boolean values that are considered false are: 0 and -0 "", the null string [], the empty list (or vector) undef Similar Non-Boolean values that are actually true are: "false" not a null string [0] a vector with a single numeric element [ [] ] outer vector is not empty [false] a vector with a single boolean element 0/0 divide by zero gives the Not A Number result.