Merge pull request #222 from dimitris-t/patch-1

Change spelling from 'an RETURN' to 'a RETURN'

ch07.asciidoc

@@ -208,7 +208,7 @@ RETURN <data>
 
 The data portion is limited to 80 bytes and most often represents a hash, such as the output from the SHA256 algorithm (32 bytes). Many applications put a prefix in front of the data to help identify the application. For example, the http://proofofexistence.com[Proof of Existence] digital notarization service uses the 8-byte prefix +DOCPROOF+, which is ASCII encoded as +44 4f 43 50 52 4f 4f 46+ in hexadecimal.
 
-Keep in mind that there is no "unlocking script" that corresponds to +RETURN+ that could possibly be used to "spend" an +RETURN+ output. The whole point of +RETURN+ is that you can't spend the money locked in that output, and therefore it does not need to be held in the UTXO set as potentially spendable—+RETURN+ is _provably un-spendable_. +RETURN+ is usually an output with a zero bitcoin amount, because any bitcoin assigned to such an output is effectively lost forever. If an +RETURN+ is referenced as an input in a transaction, the script validation engine will halt the execution of the validation script and marking the transaction as invalid. The execution of +RETURN+, essentially causes the script to "RETURN" with a FALSE and halt. Thus, if you accidentally reference an +RETURN+ output as an input in a transaction, that transaction is invalid.
+Keep in mind that there is no "unlocking script" that corresponds to +RETURN+ that could possibly be used to "spend" a +RETURN+ output. The whole point of +RETURN+ is that you can't spend the money locked in that output, and therefore it does not need to be held in the UTXO set as potentially spendable—+RETURN+ is _provably un-spendable_. +RETURN+ is usually an output with a zero bitcoin amount, because any bitcoin assigned to such an output is effectively lost forever. If a +RETURN+ is referenced as an input in a transaction, the script validation engine will halt the execution of the validation script and marking the transaction as invalid. The execution of +RETURN+, essentially causes the script to "RETURN" with a FALSE and halt. Thus, if you accidentally reference a +RETURN+ output as an input in a transaction, that transaction is invalid.
 
 A standard transaction (one that conforms to the +isStandard()+ checks) can have only one +RETURN+ output. However, a single +RETURN+ output can be combined in a transaction with outputs of any other type.