availability_cores: RuntimeDescriptor<
    [],
    Enum<
        {
            Free: undefined;
            Occupied: {
                availability: { bitsLen: number; bytes: Uint8Array };
                candidate_descriptor: {
                    core_index: number;
                    erasure_root: FixedSizeBinary<32>;
                    para_head: FixedSizeBinary<32>;
                    para_id: number;
                    persisted_validation_data_hash: FixedSizeBinary<32>;
                    pov_hash: FixedSizeBinary<32>;
                    relay_parent: FixedSizeBinary<32>;
                    reserved1: FixedSizeBinary<25>;
                    reserved2: FixedSizeBinary<64>;
                    session_index: number;
                    validation_code_hash: FixedSizeBinary<32>;
                    version: number;
                };
                candidate_hash: FixedSizeBinary<32>;
                group_responsible: number;
                next_up_on_available?: {
                    collator?: FixedSizeBinary<(...)>;
                    para_id: number;
                };
                next_up_on_time_out?: {
                    collator?: FixedSizeBinary<(...)>;
                    para_id: number;
                };
                occupied_since: number;
                time_out_at: number;
            };
            Scheduled: { collator?: FixedSizeBinary<32>; para_id: number };
        },
    >[],
>

Yields information on all availability cores as relevant to the child block. Cores are either free or occupied. Free cores can have paras assigned to them.