The Cardano Constitution, at Article IV, Section 3, requires that before withdrawal of Treasury funds, the community must have established a Net Change Limit (NCL). This means passing a NCL in a formal on-chain governance info action. The NCL represents the maximum amount of ada which may be withdrawn from the Cardano Treasury in a given period. It is a guardrail which, by definition in the Cardano Blockchain Ecosystem Constitution Definitions referenced below, protects the sustainability of the Cardano Treasury by preventing excessive withdrawals.