Define `previous` semantics (does it preserves a pre-registered ISCC-ID - declaration related)

[titusz]

The previous field allows for linking back to a previous version of a digital asset.
In context with ISCC declarations this would give an opportunity to give an ISCC-ID persistence.

Example:

• User declares ISCC-CODE:A which creates ISCC-ID:A
• User updates the digital asset.
• User redeclares the asset with new ISCC-CODE:B

Options:

1. User does not indicate previous version: A new ISCC-ID:B is minted. (A & B can probably be matched)
2. User does provide the ISCC-ID of previous version: ISCC-ID:A will be updated to ISCC-CODE:B

Notes:

With option 1 ISCC-ID:A will persistently and immutably refer to the snapshotted version of the digital asset. Other versions of the digital asset may be match-able via similarity of their linked ISCC-CODEs.

Option 2 would allow ISCC-ID:A to persistently refer to the latest version of a given asset and provide a user-controlled immutable history of its updates. This would be of use if a publicly circulated ISCC-ID should always link to the latest version of a given asset.

For option 2 to work the link to the previous version must be part of the on-chain declaration message to support stable minting semantics.