Balanced operation is intended for use in circumstances which require equal control at either end of the link. This International Standard describes HDLC balanced dass of procedures for synchronous data transmission. It covers balanced operation requirements and is consistent with an overall HDLC architecture. It uses the frame structure as defined in ISO 3309 and elements of procedure described in ISO 4335, plus addenda 1 and 21> of ISO 4335.
For the balanced operation, the link consists of two combined stations and operates in the asynchronous balanced mode. A basic repertoire of commands and responses is defined. The capability of the data link may be modified by the use of optional functions.