DDS

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DDS = Data Description Specifications

This "programming language" is used to define the layout of files, both physical and logical, interactive and prompt screens, reports, and various other kinds of objects in the 400 family.

On S/36 SSP prior to RPG/400 and DDS, we were able to use alternate index files, which were conceptually similar to the logical access files of 400 today.

The objects created by DDS do not DO anything like a program, but rather they are layouts for the data to be processed by a program.

Think similar to SDA which is one way that menus, screens, and so forth were created prior to DDS; and also UIM which BPCS uses to create help screens. Prior to RPG/400 we did not use externally defined print files, but internally defined then within the programs that were generating the reports.

Data Files

Reference Files

Physical Files

Logical Files

Display Files

Printer Files

Communication Files