Apparatus for decoding a transform coefficient block, comprising: a decoder configured to extract a significance map indicating positions of significant transform coefficients within the transform coefficient block, and then the values of the significant transform coefficients within the transform coefficient block from a data stream, with, in extracting the values of the significant transform coefficients, sequentially extracting the values by context-adaptive entropy decoding; and an associator configured to sequentially associate the sequentially extracted values with the positions of the significant transform coefficients in a predetermined coefficient scan order among the positions of the transform coefficient block, characterized in that the transform coefficient block is scanned in sub-blocks of the transform coefficient block using a sub-block scan order with, subsidiary, scanning the positions of the transform coefficients within the sub-blocks in a position sub-scan order, wherein the decoder is configured to use, in sequentially context-adapted entropy decoding the values of the significant transform coefficient values, a selected set of a number of contexts from a plurality of sets of a number of contexts, wherein the decoder is configured such that the selection of the selected set being performed for each sub-block depends on the values of the transform coefficients within a sub-block of the transform coefficient block, already having been traversed in the sub-block scan order, or such that the selection of the selected set being performed for each sub-block depends on the values of the transform coefficients of a co-located sub-block in an equally sized previously decoded transform coefficient block, wherein the sub-blocks are quadratic or rectangular. a decoder configured to extract a significance map indicating positions of significant transform coefficients within the transform coefficient block, and then the values of the significant transform coefficients within the transform coefficient block from a data stream, with, in extracting the values of the significant transform coefficients, sequentially extracting the values by context-adaptive entropy decoding; and an associator configured to sequentially associate the sequentially extracted values with the positions of the significant transform coefficients in a predetermined coefficient scan order among the positions of the transform coefficient block, characterized in that the transform coefficient block is scanned in sub-blocks of the transform coefficient block using a sub-block scan order with, subsidiary, scanning the positions of the transform coefficients within the sub-blocks in a position sub-scan order, wherein the decoder is configured to use, in sequentially context-adapted entropy decoding the values of the significant transform coefficient values, a selected set of a number of contexts from a plurality of sets of a number of contexts, wherein the decoder is configured such that the selection of the selected set being performed for each sub-block depends on the values of the transform coefficients within a sub-block of the transform coefficient block, already having been traversed in the sub-block scan order, or such that the selection of the selected set being performed for each sub-block depends on the values of the transform coefficients of a co-located sub-block in an equally sized previously decoded transform coefficient block, wherein the sub-blocks are quadratic or rectangular.