A user syntax file may contain extensions, restrictions and other modifications with respect to the basic system syntax file or the subsystem syntax files and, where applicable, with respect to the group syntax file. Possible extensions and other functional modifications are limited to statements to user programs and to commands implemented via procedures. Functional restrictions for BS2000 commands (implemented via system modules), specified in the system syntax files or the group syntax file cannot be canceled in a user syntax file.
A user syntax file may be activated, but need not be. As of SDF V4.1 several user names can be active simultaneously for each task. If a command or statement is defined in several simultaneously activated user syntax files, the definition from the last activated user syntax file is used.
If a user syntax file has the name $<userid>.SDF.USER.SYNTAX and a task under the user ID <userid> is started, this user syntax file is automatically activated following processing of the SET-LOGON-PARAMETERS command. If the user syntax file to be activated is not available at this point, e.g. because it is being processed itself, a message is output and the task is created without the user syntax file.
During the task, the user can activate the user syntax file(s) by means of the MODIFY-SDF-OPTIONS command/statement. MODIFY-SDF-OPTIONS can also be used to deactivate the user syntax file.
User syntax files are supplied in conjunction with certain products or may be generated by the user with the aid of SDF-A.