A method of video processing includes determining, for a conversion between a current block of a video and a coded representation of the video, whether a syntax element indicating usage of a skip mode for an intra-block copy (IBC) coding model is included in the coded representation according to a rule that specifies that signaling of the syntax element is based on a dimension of the current block and/or a maximum allowed dimension for a block that is coded using the IBC coding model. The method also includes performing the conversion based on the determining.