/*N SLOG_EXTRA_INTERVAL_INFOS    Notes on the Addition of Extra Interval Description.        This note is to clarify the usage of SLOG_PROF_XXX() routines        especially while the user wants to add extra interval description        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.        Also, the term interval descriptor refers to an entry in        the Display Profile, so is the term interval information,        abbrev. as _IntvlInfo_.  These 3 terms are used interchangably.        Under normal circumstances, the Display Profile table is created        by first opening the section of the logfile for storing the table        using SLOG_PROF_Open().  Then add the interval description using        SLOG_PROF_AddIntvlInfo() and close the table section by        SLOG_PROF_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_PROF_Open().  Then add the known record         definitions using SLOG_PROF_AddIntvlInfo().  However, one should        NOT call SLOG_PROF_Close() to close the table section.  Instead,        SLOG_PROF_SetExtraNumOfIntvlInfos() should be called to set        the extra number of interval description entries needed( the        number can be greater than what one actually needs ).  Then        when user encounters a new interval record type,         SLOG_PROF_AddExtraIntvlInfo() can then be called to add the new        interval record type to the Display Profile table.  This        mechanism is very similar to that of Record Definition Table.        Except for Record Definition Table, the above procedure 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.  For Display Profile, the same procedure is implmented        to simplify the interface for user to store interval description        information to the logfile, the interval description information        is NOT important till logfile needs to be displayed graphically..nN*/