In SNA, the unit of data and control information passed between path control components. A BTU can consist of one or more path information units (PIUs).; 系統(tǒng)網(wǎng)絡(luò)體系結(jié)構(gòu)(SNA)中,在通路控制部件之間傳送的數(shù)據(jù)和控制信息的單位?；緜?輸單元(BTU)可由一個或多個通路信息單元(PIU)組成。參閱blocking of PIUs。