A procedural texture is a special texture that has a 3D renderer associated with it. This means that you can change the image on the procedural texture by drawing on it. Since the procedural texture has a full 3D renderer associated with it you can even use the 3D engine to render on a texture. Procedural textures can be used on all objects in Crystal Space that can use textures.
A procedural texture is a computer generated image created using an algorithm intended to create a realistic representation of natural elements such as wood, marble, granite, metal, stone, and others.