_layer_dq_id is not present, it shall be inferred as follows: If quality id is greater than 0, ref_layer_dq_id is inferred to be equal to (DQId - 1). Otherwise (quality_id is equal to 0), ref_layer_dq_id is inferred to be equal to -1. When quality_id is equal to 0, the NAL units with DQId equal to ref_layer_dq_id shall have discardable flag equal to 0. When ref_layer_dq_id is greater than or equal to 0, it is a requirement of bitstream conformance that the layer representation with DQId equal to ef_layer_dq_id present in the bitstream. The variable MaxRefLayerDQId is set equal to the maximum value of ref_layer_dq_id for the slices of the current layer representation. When MinNoInterLayerPredFlag is equal to 0, the layer representation inside the current coded picture that has a value of DQId equal MaxRefLayerDQId is also referred to as reference layer representation. When MaxRefLayerDQId is not equal to -1, the following variables are derived as follows: RefLayerPicSizeInMbs is set equal to the value of the variable PicSizeInMbs for the reference layer representation. RefLayerPicWidthInMbs is set equal to the value of the variable PicWidthInMbs for the reference layer representation. Rec. ITU-T H.264 (01/2012) RefLayerPicHeightInMbs is set equal to the value of the variable PicHeightInMbs for the reference layer representation. RefLayerChromaFormatIde is set equal to the value of the syntax element chroma_format_idc for the reference layer representation. RefLayerChromaArrayType is set equal to the value of ChromaArrayType for the reference layer representation. RefLayerPicWidthInSamples is set equal to the value of the variable PicWidthInSamples, for the reference layer representation. RefLayerPicHeightInSamples is set equal to the value of the variable PicHeightInSamples, for the reference layer representation. RefLayerPicWidthInSamplesc is set equal to the value of the variable PicWidthInSamples for the reference layer representation. RefLayerPicHeightInSamplesc is set equal to the value of the variable PicHei