rubric_stem_capability_rating
Filtered alias of rubric_stem containing only the stems for the national_capability_rating rubric (rubric ID factbase.org/rbc/6K31VHNC19). Used to join the 21 capability rating codes (NP → AAA) into nation_capability_rating on CAPABILITY_RATING = RUBRIC_STEM_SLUG, providing descriptor text, area group, and numeric sort value from the rubric reference data without polluting the main rubric_stem cube.