If you have a running instance of Represent Boundaries, you can explore the API starting from the
/boundary-sets/ endpoint; otherwise, explore represent.opennorth.ca. You'll see links to read each boundary set's details and to browse its boundaries. Add
?format=apibrowser to the end of the URL so that you can click on links and explore the API easily. If you find your way to an individual boundary's details, you'll see links to get its shape and centroid.
For all API documentation, including filters and geospatial queries, read the API reference.