AI model knowledge frozen at training cutoff. Test through zero-shot queries (asking AI without web access). Build through multi-year corroboration campaigns in tier-1 sources likely to be in training data (academic papers, major news, industry authorities). Cannot be updated post-training — requires long-term presence strategy. Critical for brand recall in contexts where AI answers without retrieval. Assess using parametric recall protocol: query model with retrieval disabled, measure accurate characterization rate.