The two most common streaming formats for Adaptive Bitrate Streaming – Dynamic Adaptive Streaming over HTTP (DASH) and HTTP Live Streaming (HLS) – provide mechanisms for ads to be inserted into manifest files. However, there’s often a challenge to properly identify the unique ad asset(s) that are embedded in a manifest. This hampers efforts to ensure delivery and monitoring accuracy. This document proposes a clear and interoperable signaling mechanism for the signaling of creative assets in DASH and HLS. It enables, for example, unique ad asset identifiers such as those from Ad-ID.org and/or unique in-house ad asset IDs to be captured in original or stitched manifest files.