In SNA, one or more chains of request units (RUs) and their responses, that are exchanged between two LU-LU halfsessions and that represent a transaction between them.

• 系统网络体系结构(SNA)中,一个或多个请求单元(RU)及其响应链。它们在两个LU-LU(逻辑单元)话路端之间进行交换,表示它们之间的一笔交易(一次事项)处理情况。