transmission header(TH)

In SNA, control information, optionally followed by a basic information unit (BIU) or a BIU segment, that is created and used by path control to route message units and to control their flow within the network.; 在系統網絡體系結構(SNA)中的控制信息，其后可以是基本信息單位(BIU)，也可以是BIU段。標題由通路控制程序建立和使用，在網內為各報文單位選擇路由并控制報文的流通。參閱path information unit。