request/response unit (SNA) (RU)

A Request/Response Unit(RU) is a message unit in SNA architectures, it is one of three data fields of the Path Information Unit (PUI).

Structure of the Path Information Unit (PIU)

The Request/Responses Unit has a variable length and follows the Request/Response Header( RH) and contains the control information such as the Request Code, the Function Management Header, the End User data or combinations of these information. Request Units containing control information manage the operation of the network. Each request sent by a Network Addressable Unit( NAU) contains a Request Unit.

As a Response Unit, the RU data field contains information pertaining to the request. Positive responses torequests are 1 to 3 bytes long, negative responses comprise 4 to 7 bytes.