Destroy cell & OP decryption question

[Christian Seberino]

*** ''Tearing down circuits'' section of spec had a sentence I like to
humbly ask clarification on...

"The origin of a circuit always sets this error code to 0, to avoid
leaking its version."

The origin must be an OP right?  If OP sets reason byte value (error code)
to zero then how can ORs propagate the right one?  And what does it mean
'leaking its version' ?


*** As cells travel along circuits, ORs decrypt them and send them along
(reencrypted) after analyzing the payloads right?  Hence old encryption is
//replaced// with new encryption as cells move down circuit!  So I don't
understand why OP needs to do multiple decryptions for every hop along
circuit.

Chris