This restriction, which is not imposed by most computer languages, is necessary because POV-Ray allows mixing of float and vector expressions. Without the parentheses there is an ambiguity problem. The operators and their precedence are shown here. All relational operators have the same precedence. The result is always boolean.
All logical operators have the same precedence.
Note that these are not bitwise operations, they are logical. The operand C is boolean while operands A and B are any expressions. Vector Expressions POV-Ray often requires you to specify a vector . A vector is a set of related float values. Vectors may be specified using literals, identifiers or functions which return vector values.