In SNA, a request/response unit (RU) category used for requests and responses exchanged between physical units (PUs) for such purposes as activating and deactivating explicit and virtual routes and sending load modules to adjust peripheralnodes.; 在系統(tǒng)網(wǎng)絡(luò)體系結(jié)構(gòu)(SNA)中，一種請(qǐng)求或應(yīng)答單元(RU)，用于物理單元之間交換請(qǐng) 求和應(yīng)答，目的是啟用和停用顯式路由和虛擬路由。參閱link protocol, session control。