The letter is titled Limitations and Responsibilities of Platform Providers and Merchants Who Engage in Electronic Commerce While Utilizing User-Generated-Content Platforms. It outlines a wide variety of prohibited content and illegal products which may not be put or traded on online platforms.
It sets out obligations and responsibilities for the platform operators. They must use online service terms, operate complaint procedures, there are reporting requirements and they must take down illegal material (within 14 days for IP violations). There are overriding obligations to manage and monitor their platforms professionally and responsibility.
Merchants are required to provide information, observe online service terms and are prohibited from uploading banned content and products.
Many platforms are already operating with terms of service that do much of this but the time frames vary; this now provides legal teeth for online enforcement and should help IP holders taking action.