https://github.com/EOSIO/eos/blob/686f0deb5dac097cc292f735ccb47c238e763de0/libraries/chain/include/eosio/chain/controller.hpp#L87
enum class block_status {
irreversible = 0, ///< this block has already been applied before by this node and is considered irreversible
validated = 1, ///< this is a complete block signed by a valid producer and has been previously applied by this node and therefore validated but it is not yet irreversible
complete = 2, ///< this is a complete block signed by a valid producer but is not yet irreversible nor has it yet been applied by this node
incomplete = 3, ///< this is an incomplete block (either being produced by a producer or speculatively produced by a node)
};