OP_RETURN explanation

Question

Could you please explain us what is op_return used for and what does a value after op_return represent?
I've noticed that a single value repeats several times in debug log, even in different chains:

    CTxOut(nValue=0.00000000, scriptPubKey=OP_RETURN 53504b62473045022100)

What does this specific one mean and what are other posibilities?

Answer 1

OP_RETURN is the way of embedding general purpose metadata in a transaction, and is always accompanied by a zero-value output (in the chain's native currency, that is). For more technical background relating to OP_RETURN in bitcoin, which works exactly like in MultiChain, but with a much lower byte limit:

http://bitcoin.stackexchange.com/questions/29554/explanation-of-what-an-op-return-transaction-looks-like