Placeholder for the GRASS ecosystem's ordinal family: weighted Cohen's kappa (linear and quadratic weights), Gwet's AC2, and ordinal Krippendorff's alpha, each with prevalence-conditioned reference curves analogous to the binary family.
Details
Constructing the spec is legal (so users can write code that is ready
for the release); passing it to grass_report() errors until the
implementation lands. See ?grass_roadmap for the framework taxonomy.