Availability of tiles within the limits of a TileMatrix

[jerstlouis]

As raised in opengeospatial/CDBV2-2023-Summer-Workshop#4, what is the expectation about the availability of tiles within a particular TileMatrix?

Can a tile request return a 204/404 response when data is actually available at a lower resolution TileMatrix? (meaning that clients should fall back to the lower resolution).

Should we have a new OGCAPI-Hint: response header for this particular purpose?

Perhaps we should add a recommendation that servers upsample data so as to still return data when requesting a tile within the limits of a particular tile matrix

If the above is not strengthened into a requirement, add a warning for clients to not necessarily expect all tiles within the TileMatrix limit to have content, and that the client should try to fall back to a lower resolution tile matrix if a (204/404?) is returned,
and/or add such an OGCAPI-Hint: recommendation.

@joanma747