ISO/IEC 19776-3:20 15，可扩展3D（X3D），定义了集成3D图形和多媒体的系统。从概念上讲，每个X3D文件都是一个基于时间的3D空间，其中包含可以通过各种机制动态修改的图形和听觉对象。ISO/IEC 19776的这一部分定义了X3D中的抽象对象到以紧凑二进制形式编写的特定X3D编码的映射。 使用压缩二进制编码编码的每个X3D文件: a.支持X3D抽象规范ISO/IEC 19775中定义的X3D文件的所有用途； b.利用几何和信息论压缩技术，以压缩的二进制格式对X3D结构进行编码。 使用压缩二进制编码编码的X3D文件可以从使用其他X3D编码的文件引用，并且其本身可以引用使用其他X3D编码编码的其他X3D文件。使用多种编码的X3D文件集只能由支持所有使用的X3D编码的浏览器处理。

ISO/IEC 19776-3:2015, Extensible 3D (X3D), defines a system that integrates 3D graphics and multimedia. Conceptually, each X3D file is a 3D time-based space that contains graphic and aural objects that can be dynamically modified through a variety of mechanisms. This part of ISO/IEC 19776 defines a mapping of the abstract objects in X3D to a specific X3D encoding written out in a compact binary form.
Each X3D file encoded using the Compressed binary encoding:
a. supports all of the purposes of X3D files defined in the X3D abstract specification ISO/IEC 19775;
b. encodes X3D constructs in a compressed binary format, taking advantage of geometric and information-theoretic compression techniques.
X3D files encoded using the Compressed binary encoding may be referenced from files using other X3D encodings, and may itself reference other X3D files encoded using other X3D encodings. Sets of X3D files that use multiple encodings can only be processed by browsers that support all of the utilized X3D encodings.