对指定账户下所有未完成挂单发起批量撤单操作。支持按市场筛选,不指定市场时默认撤销所有市场的挂单。覆盖待提交、已委托、部分成交等状态的订单,单次最多处理 1000 笔。各订单独立处理,单笔失败不影响其余订单执行。最终撤单结果以上手反馈为准。Initiates a bulk cancel operation for all open orders under the specified account. Supports filtering by market; if no market is specified, all markets are included by default. Covers orders in states including pending submission, commissioned, and partially filled, with a maximum of 1,000 orders processed per request. Each order is cancelled independently — a failure on one order does not affect the execution of others. The final cancellation result is subject to upstream feedback.