Find what limits and opportunities we have around regional data

We have a separate Canadian data region. The purpose of this region is to keep the data separate from the US data. It therefore seems like it's not ok to simply merge all of the tables (otherwise we would never have created the region). However, the exact rules are quite fuzzy.

There is a risk that without knowing what we are and aren't allowed to do we will:

* Do something illegal or which causes reputational harm
* Waste effort working around imagined issues

We need to work out some guidelines to ensure we are being as strict as we need to, but no more.

## A worked example

* It's likely the regional data must be at rest in the region (in a DB in Canada)
* We know we can move the data to a browser world wide to view it
* This means data is moving from in region to out is permitted even for sensitive fields
* But at some point there is a line where processing or volume becomes unacceptable
* Where is that point?

## Questions

* What are the broad principals at play from a legal point of view?
* Are there additional contractual or reputation requirements that bind us beyond the legal minimum?
* The HECVAT might be one source of useful info here
* CIAQ also?
* Do we have contractual levers we can pull which increase our flexibility?
* Are the rules different for data at rest vs. processing?
* For example, can we process data in the US region, if it resides in CA?
* What about caching?
* How long counts as caching and how long is storage?
* What general types of data (if any) are we:
* Prohibited from exporting from the Canadian region?
* Always safe to export from the Canadian region?
* Does what we do for Canada apply to other likely new regions we might expand into?

## Possible outcomes

It could be that we determine we do not understand the rules around regional data. In this case we should say so and then take a maximalist approach.