You require at least the basic system syntax file in order to work with SDF. It contains the definitions of the domains, the standard statements and the SDF-specific commands (from the SDF domain) as well as the system-wide global information settings. The syntax file SYSSDF.SDF.048 is activated for this purpose by default. Systems support can make the modifications (e.g. restrict functions) with the SDF-A (or SDF-U) utility routine. Modifications apply to all users of the system.
When SDF starts, the name of the basic system syntax file is read from the SDF parameter file and the file is automatically activated.
During a session, system administration can replace the activated basic system syntax file with another by means of the MODIFY-SDF-PARAMETERS command. A change to the basic system syntax file during the session immediately affects all existing and future tasks.