timespec - time in seconds and nanoseconds

       Describes times in seconds and nanoseconds.

       tv_nsec is of an implementation-defined signed type capable of holding the specified range.  Under glibc,
       this  is  usually  long, and longlong on X32.  It can be safely down-cast to any concrete 32-bit integer
       type for processing.

       POSIX.1-2001.

       Standard C library (libc)

       timespec - time in seconds and nanoseconds

       The following headers also provide this type: <aio.h>, <mqueue.h>, <sched.h>, <signal.h>, <sys/select.h>,
       and <sys/stat.h>.

clock_gettime(2), clock_nanosleep(2), nanosleep(2), timerfd_gettime(2), timer_gettime(2),  time_t(3type),
       timeval(3type)

Linux man-pages 6.9.1                              2024-05-02                                    timespec(3type)

       C11, POSIX.1-2008.

#include<time.h>structtimespec{time_ttv_sec;   /* Seconds */
           /* ... */  tv_nsec;  /* Nanoseconds [0, 999'999'999] */
       };

       Prior to C23, tv_nsec was long.