The reltimespec structure represents relative time. This structure is similar to the timespec structure, except that the first field is signed in the reltimespec structure. (The field is unsigned in the timespec structure.) You can find the reltimespec structure in the dce/utc.h header file.
The reltimespec structure declaration follows:
struct reltimespec {
time_t tv_sec; /* Seconds of relative time */
long tv_nsec; /* Additional nanoseconds of */
/* relative time */
} reltimespec_t;