When a BDT request is issued by a batch job, the request is processed by a BDT batch processor (BDTBATCH) which issues an SVC to route it to IGX00034. This module invokes the BDT language processor (BDTLP). BDTLP builds the first BDT control block, called the BSID, to contain the user’s request. The new BSID is passed to BDTSSBDT by the subsystem interface (SSI).