What means "messege" in the bitcoin blockchain? [elliptic curve cryptography] I am stuck with one question in my research.
I found some mentions that bitcoin(or blockchain) is a messeging system, I played with couple curve encoding algorithms and it was like:

Curve params, priv key, pub key or coordinates + messege = signature.

Its easy to read about it but I stuck to figure out what "messege" is in the bitcoin blockchain info? 
How this related to tx hashes? tx amount? what actually we encoding during the transaction and how to get this input/outut in readable format.

Thanks
The signed message will be some portion of a Bitcoin transaction.  The Bitcoin code has specific rules for what the signed message needs to be.  The signed message needs to include any data that you don't want to be modifiable by a third party, so it should include all the output addresses/scripts and the Bitcoin amounts being sent to those outputs.  The message cannot be the entire transaction, because the transaction includes the signature itself (before segwit came along) and the signature cannot sign itself.  I don't know the exact details, but you can read up on the Bitcoin transaction format to learn more.