**How was the issue detected?** [HDR Nova AV2 Verification](https://www.hdrnova.com/av2-verification) **What version / commit were you testing with?** 29e572b3 **What steps will reproduce the problem?** We are making verification streams for CONFIG_OUTPUT_FRAME_BASED_ON_ORDER_HINT_ENHANCEMENT, but have concerns about the reference code. The document E056 changes the semantics of showable_frame. With the new semantics, if equal to 1, a frame can be automatically output. If equal to 0, the show existing frame mechanism can be used. There are two concerns: 1. How are forward key frames meant to be supported now? A frame is treated as a forward keyframe if showable_frame is equal to 1 and the show existing frame mechanism is used. However, when showable_frame is equal to 1 the frame can be automatically output, but the automatic output does not trigger the side effects of forward key frames. 2. To allow the use of show_existing_frame and stop automatic output, showable_frame needs to be set equal to 0, but in this case the code will infer that no film grain needs to be applied. These concerns could be addressed by keeping the old showable_frame bit and semantics, and instead adding a new bumpable_frame bit to indicate which frames can be automatically output (which is only present if enable_frame_output_order is equal to 1).