Glossary
acceptable-use
License or terms-of-service clauses that prohibit certain uses (weapons, surveillance, harassment, child sexual abuse material), common on open-weight licenses but rejected by the strict open-source definition.
A list of prohibited uses attached to many open weightsweightsA model release that publishes the trained parameters under some downloadable license, distinct from "open source" which (per OSAID) also requires data and training-code openness. Open full entry licenses. The LlamaweightsMeta's open-weight model family, the most widely deployed open release through 2024 to 2026, released under the source-available Community License with an MAU cap and acceptable-use clause. Open full entry AUP bars use for weapons, CSAM, harassment, and impersonation, among others. GemmaweightsGoogle's open-weight model family derived from Gemini research, with source-available licensing that includes an acceptable-use clause and license-revocation hook. Open full entry ’s terms have a similar list. Most “ethical source” licenses (Hippocratic, Anti-996, OpenRAIL) work the same way.
The clauses are non-controversial in spirit and controversial in form. On the substance, almost no one defends the prohibited uses. On the form, the OSIgovernanceThe nonprofit that maintains the canonical Open Source Definition for software since 1998, and the OSAID definition for AI as of 2024. Open full entry position is that any use restriction violates the Open Source Definition’s “no discrimination against fields of endeavor” clause. The result: LlamaweightsMeta's open-weight model family, the most widely deployed open release through 2024 to 2026, released under the source-available Community License with an MAU cap and acceptable-use clause. Open full entry and most ethical-source licenses are not OSAIDgovernanceThe OSI's October 2024 definition of "open source AI," requiring not just weights but enough information about data, code, and architecture for third parties to reproduce the system. Open full entry -compliant even when the prohibited list is uncontroversial.
For users the practical implication is verification burden. A licensee accepting an acceptable-use clause is taking on enforcement risk if downstream use violates it; the licensor may revoke the license. Apache 2.0governanceA permissive open-source license used by most open-weight model releases (Llama from 4 onward partial, Qwen, Mistral, DeepSeek, Falcon), allowing commercial use without acceptable-use restrictions. Open full entry weights carry no such revocation hook.