es NAL units from a scalable bitstream, e.g. in order to adapt the bitstream to a transmission channel or the capabilities of a receiving device, and keeps the present layer dependency change SEI messages, it might need to modify the content of some of the layer dependency change SEI messages and remove some other layer dependency change SEI messages in order to obtain a bitstream conforming to this Recommendation | International Standard. For the following specification of this clause, the scalable layer with layer identifier equal to the current value of layer_id i is referred to as the current scalable layer and the representation of the current scalable layer is referred to as current scalable layer representation. layer_dependency_info_present_flag[ equal to 1 specifies that one or more syntax elements dependent_layer_id_delta_minus1[i][j indicating the layer dependency information for the current scalable layer are present in the layer dependency change SEI message. layer_dependency_info_present_flag| equal to 0 specifies that the syntax elementlayer_dependency_info_src_layer_id_delta_minus1[i] for the current scalable layer is present in the layer dependency change SEI message. num_directly_dependent_layers[i] specifies number syntax elements directly_dependent_layer_id_delta_minus1[i][j that are present for the current scalable layer. The value of num_directly_dependent_layers shall be in the range of 0 to 255, inclusive. irectly_dependent_layer_id_delta_minus1[i]jlr plus 1 indicates the difference between the value of layer for the current scalable layer and the layer identifier of a particular scalable layer, on which the current scalable layer directly depends. The value of directly_dependent_layer_id_delta_minus1[i][j] shall be in the range of 0 to layer id| 1, inclusive. The layer identifier of the particular scalable layer, on which the current scalable layer directly depends, is equal to layer_ic -directly_dependent_layer_id_delta_minus1 - - 1. The most recent scalability information SEI message in