Stock rules are a feature of ServiceNow Hardware Asset Management that allow you to automate the replenishment of stock levels in your stockrooms1.
Stock rules define the minimum and maximum quantities of a specific model that you want to keep in a stockroom, as well as the reorder point and quantity1.
When the stock level of a model falls below the reorder point, a stock order is automatically generated to replenish the stockroom to the maximum quantity1.
You can create and manage stock rules by navigating to Hardware Asset Management > Model Management > Stock Rules1. Reference:
1: Stock rules - ServiceNow Docs.