In BS2000/OSD V1.0 and higher the SDF command language (System Dialog Facility) replaced the ISP command language. Commands from the old command language ISP continue to be supported for the sake of compatibility, but the full functionality of SDF can be exploited only with commands and statements employing the SDF syntax (ISP commands are checked only with regard to their names).
SDF is a command language which allows convenient interactive input of commands and program statements. Dialog guidance makes input easier, informs the user of the functions of individual operands as required, and permits a correction dialog if an input error is detected. Extensive knowledge of SDF command input is not required, as the brief examples in this section are sufficiently informative. Depending on your system configuration, your output screens may differ from those in the examples (e.g. in the range of commands offered).
SDF offers the following special features:
Mnemonics
The command language itself already simplifies the use of commands: the names of commands, operands and constant operand values have been chosen such that they reflect the function or use. In addition, analogous facts are described by means of identical keywords throughout the command set.
Abbreviation mechanism
Long inputs are not problematic. In interactive mode, SDF offers many ways of abbreviating your inputs. Most operands, for example, have a preset operand value, the default value. You need only specify these operands if you want to change their values. If any of the defaults do not correspond to the values you use most frequently, you can define your own default values for your task.
You can also abbreviate names: within names or partial names you can leave out from right to left as many characters as you wish, provided the name remains recognizable in its context. Bear in mind that a command name is unique among all command names, and an operand name is unique among all operand names of the command on the appropriate structural level.
Line or menu mode
You can enter your input either directly in line mode (unguided dialog, "Input in unguided dialog ") or by switching to a menu-driven input mode (guided dialog, "Input in guided dialog "). Guided dialog supports three levels of guidance, which differ in the range of menu options they offer. You can change your input mode at any time.
Error correction dialog
SDF checks your input for syntax errors before the command is executed. If it detects an error, it switches automatically to a correction dialog, depending on the level of guidance set.
Reconstruction of commands
SDF can save your inputs to a buffer. This enables you to retrieve any such saved input and use it again (see "Reusing previous inputs ").
SDF information system (help)
You can call SDF help by entering a question mark. Depending on the position of the question mark within the input and the level of guidance set, SDF provides various forms of support during command input. These include a selection menu for certain commands, an operand form for a specific command, or information on a specific operand.
SDF offers the simplest form of support in unguided dialog:
By entering a question mark you can switch to guided dialog for the input of one command only. When you have entered the command you will be returned to the original input mode - unguided dialog. This type of input is called temporary guided dialog (see "Input in temporarily guided dialog ").