A method of video processing is provided. The method includes: determining, for a conversion between a current video block of a video and a coded representation of the video, a mode of operation of a generalized bi-prediction (GBi) coding tool in which a prediction of the current video block uses a final predictor corresponding to a non-uniformly weighted sum of predictors from two reference lists; and performing the conversion based on the determining, wherein a field in the coded representation corresponds to the mode of operation and a value of the field indicates whether the GBI coding tool is enabled or disabled for the current video block.