Once a document, such as Bill of lading has been created on the platform, issuer can still delete or change it. 

But once an envelope with this document has been transferred away from the Issuer (in someone else's possession) it can not be changed by anyone.

If parties later discover an error in the document, the procedure how to amend it is as follows. 

The document must be transferred (returned) to the issuer, along with additional document or note requesting the change. 

Based on this information Issuer can now (any only now that they have the document they have issued back in their possession), destroy this document and issue a new (corrected) one in its place (use of the same document number is allowed).

Destroying existing document is mandatory, as blockchain is immutable, which means that documents already written in the Blockchain are unchangeable.

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