The RRD is an extensible infrastructure that enables other components and stack products to add custom extensions, like generators and handlers, to the RRD extension.

RRD 是可扩展的基础结构，可以使其他组件和堆栈产品能够将自定义扩展（如生成器和处理程序）添加到 RRD 扩展。

youdao

Evidently two years wasn't long enough to find an acceptable industry standard stack to deliver video over IP, so TiVo and the cable industry requested an extension.

ENGADGET: FCC clarifies set-top box IP interface requirement and extends deadline to 2014