Got it, thank you. Guess I'm unclear about the purpose of order.trailStopPrice and order.lmtPriceOffset fields. Is the following accurate?
order.trailStopPrice is calculated by the system as (1-trailingPercent) * (last price)
order.lmtPriceOffset is provided by the user
order.trailStopPrice is the price at which the order gets triggered with a limit price of (order.trailStopPrice - order.lmtPriceOffset)