Proposal:Relation:postal code

Note that there is another boundary relation system with boundary=postal_code which is already in wide use.

This Relation could replace postal_code=* on ways. There should be one relation per postal code, grouping all streets with this postal code.

Members

Way or Node	Role	Recurrence?	Discussion
	(blank)	zero or more	street with this postal code

One might want to add other objects associated with the postal code to the relation, e.g., buildings. On the other hand, if they're already associated with a street in the relation, this isn't necessary.
If a street consists of several ways, you can add a Relation:street to the postal code relation instead of the separate ways.

Key	Value	Discussion
type	postal_code	defines the type of the relation
postal_code	*	the postal code