Beginning in the 1990s and 2000s, municipalities implemented " single stream" recycling programs.
从20世纪90年代以及21世纪前十年开始，市政当局实施了“单流制”回收计划。
英语百科
MPEG program stream
（重定向自Program Stream）
Program stream (PS or MPEG-PS) is a container format for multiplexing digital audio, video and more. The PS format is specified in MPEG-1 Part 1 (ISO/IEC 11172-1) and MPEG-2 Part 1, Systems (ISO/IEC standard 13818-1/ITU-T H.222.0). The MPEG-2 Program Stream is analogous and similar to ISO/IEC 11172 Systems layer and it is forward compatible.