diff --git a/src/blockheader.rs b/src/blockheader.rs
index 50a8d9c35..6abbbdff7 100644
--- a/src/blockheader.rs
+++ b/src/blockheader.rs
@@ -1,31 +1,66 @@
 use util::hash::*;
+use util::bytes::*;
 use util::uint::*;
 use util::rlp::*;
 
-pub struct BlockHeader {
+pub static ZERO_ADDRESS: Address = Address([0x00; 20]);
+pub static ZERO_H256: H256 = H256([0x00; 32]);
+pub static ZERO_LOGBLOOM: LogBloom = H2048([0x00; 256]);
+
+pub type LogBloom = H2048;
+
+#[derive(Debug)]
+pub struct Header {
 	parent_hash: H256,
-	ommers_hash: H256,
-	beneficiary: Address,
-	state_root: H256,
-	transactions_root: H256,
-	receipts_root: H256,
-	log_bloom: H2048,
-	difficulty: U256,
-	number: U256,
-	gas_limit: U256,
-	gas_used: U256,
 	timestamp: U256,
-	mix_hash: H256,
-	nonce: H64
+	number: U256,
+	author: Address,
+
+	transactions_root: H256,
+	uncles_hash: H256,
+	extra_data: Bytes,
+
+	state_root: H256,
+	receipts_root: H256,
+	log_bloom: LogBloom,
+	gas_used: U256,
+	gas_limit: U256,
+
+	difficulty: U256,
+	seal: Vec<Bytes>,
 }
 
-impl Decodable for BlockHeader {
-	fn decode<D>(decoder: &D) -> Result<Self, DecoderError>  where D: Decoder {
+impl Header {
+	pub fn new() -> Header {
+		Header {
+			parent_hash: ZERO_H256.clone(),
+			timestamp: BAD_U256.clone(),
+			number: ZERO_U256.clone(),
+			author: ZERO_ADDRESS.clone(),
+
+			transactions_root: ZERO_H256.clone(),
+			uncles_hash: ZERO_H256.clone(),
+			extra_data: vec![],
+
+			state_root: ZERO_H256.clone(),
+			receipts_root: ZERO_H256.clone(),
+			log_bloom: ZERO_LOGBLOOM.clone(),
+			gas_used: ZERO_U256.clone(),
+			gas_limit: ZERO_U256.clone(),
+
+			difficulty: ZERO_U256.clone(),
+			seal: vec![],
+		}
+	}
+}
+
+impl Decodable for Header {
+	fn decode<D>(decoder: &D) -> Result<Self, DecoderError> where D: Decoder {
 		decoder.read_list(| d | {
-			let blockheader = BlockHeader {
+			let blockheader = Header {
 				parent_hash: try!(Decodable::decode(&d[0])),
-				ommers_hash: try!(Decodable::decode(&d[1])),
-				beneficiary: try!(Decodable::decode(&d[2])),
+				uncles_hash: try!(Decodable::decode(&d[1])),
+				author: try!(Decodable::decode(&d[2])),
 				state_root: try!(Decodable::decode(&d[3])),
 				transactions_root: try!(Decodable::decode(&d[4])),
 				receipts_root: try!(Decodable::decode(&d[5])),
@@ -35,20 +70,21 @@ impl Decodable for BlockHeader {
 				gas_limit: try!(Decodable::decode(&d[9])),
 				gas_used: try!(Decodable::decode(&d[10])),
 				timestamp: try!(Decodable::decode(&d[11])),
-				mix_hash: try!(Decodable::decode(&d[12])),
-				nonce: try!(Decodable::decode(&d[13]))
+				extra_data: try!(Decodable::decode(&d[12])),
+				seal: vec![],
 			};
+			// TODO: fill blockheader.seal with (raw) list items index 12..)
 			Ok(blockheader)
 		})
 	}
 }
 
-impl Encodable for BlockHeader {
+impl Encodable for Header {
 	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		encoder.emit_list(| e | {
 			self.parent_hash.encode(e);
-			self.ommers_hash.encode(e);
-			self.beneficiary.encode(e);
+			self.uncles_hash.encode(e);
+			self.author.encode(e);
 			self.state_root.encode(e);
 			self.transactions_root.encode(e);
 			self.receipts_root.encode(e);
@@ -58,8 +94,8 @@ impl Encodable for BlockHeader {
 			self.gas_limit.encode(e);
 			self.gas_used.encode(e);
 			self.timestamp.encode(e);
-			self.mix_hash.encode(e);
-			self.nonce.encode(e);
+			self.extra_data.encode(e);
+			// TODO: emit raw seal items.
 		})
 	}
 }
diff --git a/src/lib.rs b/src/lib.rs
index ce40bc439..07fea5389 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -69,13 +69,19 @@
 //!       sudo ldconfig
 //!       ```
 
-#[macro_use] 
+#[macro_use]
 extern crate log;
-extern crate ethcore_util as util;
-
+extern crate env_logger;
 #[cfg(feature = "jit" )]
 extern crate evmjit;
+extern crate ethcore_util as util;
 
+//use util::error::*;
+pub use util::hash::*;
+pub use util::uint::*;
+pub use util::bytes::*;
+
+pub mod state;
 pub mod blockheader;
 pub mod transaction;
 pub mod networkparams;
diff --git a/src/transaction.rs b/src/transaction.rs
index e8905fd3c..fc2159c8a 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -1,4 +1,5 @@
 use util::hash::*;
+use util::bytes::*;
 use util::uint::*;
 use util::rlp::*;
 
@@ -8,7 +9,7 @@ pub struct Transaction {
 	gas: U256,
 	receive_address: Option<Address>,
 	value: U256,
-	data: Vec<u8>,
+	data: Bytes,
 }
 
 impl Transaction {