/*N SLOG_EXTRA_RECDEFS    Notes on the Addition of Extra Record Definitions        This note is to clarify the usage of SLOG_RDEF_XXX() routines        especially while the user wants to add extra record definitions        to the logfile when the process of addition of interval records         to the logfile has been started, for instance if one needs to        add user marker interval records.        Under normal circumstances, the record definition table is created        by first opening the section of the logfile for storing the table        using SLOG_RDEF_Open().  Then add the record definition using        SLOG_RDEF_AddRecDef() and close the table section by        SLOG_RDEF_Close().        In the case that the logfile involves interval records whose        interval type are NOT known until the process of inserting        of the interval records to the logfile has been started, one         should open the SLOG_RDEF_Open().  Then add the known record         definitions using SLOG_RDEF_AddRecDef().  However, one should        NOT call SLOG_RDEF_Close() to close the table section.  Instead,        SLOG_RDEF_SetExtraNumOfRecDefs() should be called to set        the extra number of record definition entries needed( the        number can be greater than what one actually needs ).  Then        when user encounters a new interval record type,         SLOG_RDEF_AddExtraRecDef() can then be called to add the new        interval record type to the record definition table.  This        has to be done before adding the interval record to the logfile        using SLOG_Irec_ToOutputStream() which does NOT allow interval        record of with unknown interval type to the record definition        table..nN*/