PE78: Reassignment of persistent identifiers

The following options re the reassignment of persistent identifiers
are suggested in the current errata document:

1. Make non-reassignment a recommendation, adding text at line 3325:

A given value, once associated with a principal, SHOULD NOT be
assigned to a different principal at any time in the future.

2. Make non-reassignment a requirement, adding text at line 3325:

A given value, once associated with a principal, MUST NOT be assigned
to a different principal at any time in the future.

IMO, option 1 is not a viable option.  Either a persistent identifier
MAY be reassigned or a persistent identifier MUST NOT be reassigned.
There is no middle ground.

Tom