Explanation

In order-driven markets, there are two main pricing rules:

1. Discriminatory Pricing Rule (also called continuous pricing rule):

   • Each trade occurs at the limit price of the order that initiated the trade
   • Different trades can occur at different prices
   • This is a continuous market where orders are matched as they arrive
   • The trade price is determined by the limit price of the incoming order

2. Uniform Pricing Rule (also called call market pricing rule):

   • All trades occur at the same price (the clearing price)
   • Orders are batched and executed at a single price that maximizes trading volume
   • This is typical in call markets where trading occurs at specific times

Given that the question states "the trade price is determined by the limit price of an order," this describes the discriminatory pricing rule where each trade price is determined by the specific limit order that initiated the transaction.

Derivative pricing rule is not a standard term in market microstructure for describing order-driven market pricing rules.

Key Takeaway: When trade prices vary based on individual limit orders, it's discriminatory pricing; when all trades occur at a single clearing price, it's uniform pricing.