Decoder for decoding a coded signaling of a multi-tree structure from a data stream, the signaling of the multi-tree structure prescribing a spatial multi-tree subdivision of a tree root block according to which the tree root block is recursively multi-partitioned into leaf blocks (152a, 152b, 154a, 156a, 156b, 156c, 156d, 154c, 154d, 152d), wherein the spatial multi-tree subdivision is a quadtree-subdivision, the coded signaling comprising a sequence of flags associated with nodes of the multi-tree structure in a depth-first order, and each flag specifying whether an area of the tree root block corresponding to the node with which the respective flag is associated, is multi-partitioned, characterized in that the decoder being configured to sequentially entropy-decode the flags using probability estimation contexts which are the same for flags associated with nodes of the multi-tree structure lying within the same hierarchy level of the multi-tree structure, but different for nodes of the multi-tree structure lying within different hierarchy levels of the multi-tree structure, wherein the decoder is configured to decode signalings of multi-tree structures prescribing a spatial multi-tree subdivision of a plurality of tree root blocks which, in turn, are leaf blocks of another multi-tree sub-division of a greater two-dimensional portion, in a depth-first traversal order defined among the plurality of tree root blocks, and wherein the coding signalings of the multi-tree structures each comprise a sequence of flags associated with nodes of the respective multi-tree structure in depth-first traversal order, and each flag specifying whether an area of the respective tree root blocks corresponding to the node with which the respective flag is associated, is multi-partitioned, the decoder being configured to sequentially entropy-decode the flags using probability estimation contexts which are the same for flags associated with areas of the same size, wherein the decoder is configured for deriving minimum and maximum admissible block sizes for the spatial multi-tree subdivision from side information of the data stream. characterized in that the decoder being configured to sequentially entropy-decode the flags using probability estimation contexts which are the same for flags associated with nodes of the multi-tree structure lying within the same hierarchy level of the multi-tree structure, but different for nodes of the multi-tree structure lying within different hierarchy levels of the multi-tree structure, wherein the decoder is configured to decode signalings of multi-tree structures prescribing a spatial multi-tree subdivision of a plurality of tree root blocks which, in turn, are leaf blocks of another multi-tree sub-division of a greater two-dimensional portion, in a depth-first traversal order defined among the plurality of tree root blocks, and wherein the coding signalings of the multi-tree structures each comprise a sequence of flags associated with nodes of the respective multi-tree structure in depth-first traversal order, and each flag specifying whether an area of the respective tree root blocks corresponding to the node with which the respective flag is associated, is multi-partitioned, the decoder being configured to sequentially entropy-decode the flags using probability estimation contexts which are the same for flags associated with areas of the same size, wherein the decoder is configured for deriving minimum and maximum admissible block sizes for the spatial multi-tree subdivision from side information of the data stream.