Unspecified or Unknown Entity - Relationship statement or entity statement

[kathryn-ods]

While working on the PSC register @odscrachel mentioned it was unclear whether to represent unknown entities within the interestedParty field of a relationship statement or using an entity statement with unspecifiedEntityDetails

We agreed in this case to use the interestedParty field.

Does having both of these as options result in some redundancy in the schema? Or is there a reason that an unknown entity might need to be declared independently of a relationship statement?

[kathryn-ods]

links to #389