Creating distinct properties for canonicalization and labeling coterminous districts

[jloutsenhizer]

Presently in the repository there are several aliases established in a few different countries. These are used in two different ways:

• In some cases these are used to define a canonical ID for the division
  • see aliases.csv for Germany.
• In other cases this is used to denote that the two divisions are coterminous
  • see many examples from aliases.csv in United States

When attempting to canonicalize OCD IDs via sameAs you run into some issues:

• Divisions which are coterminous have the same canonical ID, leading to issues like the one described in Add cd:at-large to states with only one congressional district #110
• There's no guarantee that these divisions will remain coterminous in the future. As described in Incorrect Country Code used for United Kingdom #184. So the canonical ID for a division can shift.

Ideally there should be a coterminousWith property that can be used to annotate in the OCD ID csv files which divisions are coterminous. Then sameAs can be exclusively for canonicalization.

[jpmckinney]

coterminousWith sounds good to me. Can you create a PR to update the OCDEP? (I'm not sure if the practice is to update existing OCDEPs, or only create new ones. @jamesturk ?)

[jloutsenhizer]

Happy to send a PR once it's determined if I should update an existing OCDEP or if it should be a new one