POV-Ray knows when it needs a vector of a particular type and will promote a float into a vector if need be. For example the POV-Ray scale statement requires a three component vector. Versions of POV-Ray prior to 3.0 only allowed such use of a float as a vector in various limited places such as scale and turbulence. However you may now use this trick anywhere. Section 7.1.5 Specifying Colors POV-Ray often requires you to specify a color.
Colors consist of five values or color components.
The first three are called red , green and blue. They specify the intensity of the primary colors red, green and blue using an additive color system like the one used by the red, green and blue color phosphors on a color monitor. The 4th component, called filter , specifies the amount of filtered transparency of a substance. Some real-world examples of filtered transparency are stained glass windows or tinted cellophane. The light passing through such objects is tinted by the appropriate color as the material selectively absorbs some frequencies of light while allowing others to pass through.