1.block_header

eos_read/libraries/chain/include/eosio/chain/block_header.hpp

block_header

struct block_header
   {
      block_timestamp_type             timestamp;
      account_name                     producer;

      /**
       *  By signing this block this producer is confirming blocks [block_num() - confirmed, blocknum()) 
       *  as being the best blocks for that range and that he has not signed any other
       *  statements that would contradict.  
       *
       *  No producer should sign a block with overlapping ranges or it is proof of byzantine
       *  behavior. When producing a block a producer is always confirming at least the block he
       *  is building off of.  A producer cannot confirm "this" block, only prior blocks.
       */
      uint16_t                         confirmed = 1;  

      block_id_type                    previous;

      checksum256_type                 transaction_mroot; /// mroot of cycles_summary
      checksum256_type                 action_mroot; /// mroot of all delivered action receipts


      /** The producer schedule version that should validate this block, this is used to
       * indicate that the prior block which included new_producers->version has been marked
       * irreversible and that it the new producer schedule takes effect this block.
       */
      uint32_t                          schedule_version = 0;
      optional<producer_schedule_type>  new_producers;
      extensions_type                   header_extensions;


      digest_type       digest()const;
      block_id_type     id() const;
      uint32_t          block_num() const { return num_from_id(previous) + 1; }
      static uint32_t   num_from_id(const block_id_type& id);
   };

2.signed_block_header

signed_block_header

struct signed_block_header : public block_header
   {
      signature_type    producer_signature;
   };

3.signed_block

signed_block

eos_read/libraries/chain/include/eosio/chain/block.hpp

struct signed_block : public signed_block_header {
      using signed_block_header::signed_block_header;
      signed_block() = default;
      signed_block( const signed_block_header& h ):signed_block_header(h){}

      vector<transaction_receipt>   transactions; /// new or generated transactions
      extensions_type               block_extensions;
   };

4.

eos_read/plugins/chain_plugin/chain_plugin.cpp

id, block_num, ref_block_prefix

fc::variant read_only::get_block(const read_only::get_block_params& params) const {
return fc::mutable_variant_object(pretty_output.get_object())
("id", block->id())
("block_num",block->block_num())
("ref_block_prefix", ref_block_prefix);
}