A model whose trained weights are publicly released, allowing anyone to run, fine-tune, or modify it without API access or per-token payment.
Broad technical consensus on what this term means. Disagreements that invoke it are about the world, not the word.
Claim 5.2 turns entirely on whether open-weight models reach parity for economic use cases, and the concept is also load-bearing in 6.1–6.2 (Chinese labs releasing open weights) and B4 (commoditization). The scaffold has 'foundation-model' but says nothing about the open/closed access distinction that is central to the competitive and regulatory arguments throughout the map.