In SNA, a field in a FID4 transmission header that contains a subarea address, which combined with the element address in the origin element field (OEF), gives the complete network address of the originating network addressable unit (NAU).; 在系統(tǒng)網(wǎng)絡(luò)體系結(jié)構(gòu)(SNA)中,格式標(biāo)識(shí)符4(FID4)傳輸報(bào)頭中的一個(gè)字段,它包含一個(gè)子區(qū)地 址,該地址和源單元字段中的單元地址組合在一起,給出源網(wǎng)絡(luò)可尋址單元(NAU)的完整 的網(wǎng)絡(luò)地址。對(duì)照destination subarea field (DSAF)。 參閱format identification (FID) field。