The PLY format describes an object as a collection of vertices, faces and other elements, along with properties such as color and normal direction that can be attached to these elements. A PLY file contains the description of exactly one object. The PLY format is NOT intended to be a general scene description language, a shading language or a catch-all modeling format. This means that it includes no transformation matrices, object instantiation, modeling hierarchies, or object sub-parts. Most PLY files include this core information.
Applications can create new properties that are attached to elements of an object.
For example, the properties red, green and blue are commonly associated with vertex elements. New properties are added in such a way that old programs do not break when these new properties are encountered. Properties that are not understood by a program can either be carried along uninterpreted or can be discarded. In addition, one can create a new element type and define the properties associated with this element. New elements can also be carried along or discarded by programs that do not understand them.