1. A device for encoding video data, the device comprising: one or more computer-readable storage media configured to store video data; and one or more processors configured to: generate a bitstream that comprises an encoded representation of the video data, the bitstream comprising a plurality of layers, wherein: Network Access Layer (NAL) units of the bitstream having different layer identifiers belong to different layers of the plurality of layers, and the one or more processors are configured such that, as part of generating the bitstream, the one or more processors include, in the bitstream, a syntax element indicating a number of different partitioning schemes of an output layer set, wherein the number of different partitioning schemes for the output layer set is greater than 1 and, for each respective partitioning scheme of the partitioning schemes for the output layer set, the respective partitioning scheme is a respective set of disjoint partitions whose union forms the output layer set, each respective partition of the respective set of disjoint partitions containing one or more layers of the plurality of layers; and output the bitstream.