Disclosed and systems, methods and devices for video processing. An exemplary method for video processing includes: determining for a current video block, an indication which indicates that an affine merge with motion vector difference (MMVD) mode is applied to the current video block; performing a conversion between the current video block and a bitstream representation of a current video block based on the indication, the indication being activated based on the usage of at least one merge list for the current video block.