To make an IDMS data source accessible to FOCUS, you need to describe the IDMS data source using FOCUS syntax. The FOCUS description is maintained in two files, a Master File and an associated Access File. FOCUS uses the Master File to interpret requests and to generate reports. The adapter uses the Access File to make the DML and LRF calls that retrieve IDMS records. Use your system editor or the AUTOIDMS facility to create the file descriptions. You only need to create the file descriptions once for each IDMS subschema.