Nanosecond timing

Names specified here
Name	Description			Source
`struct timespec`	Nanosecond time type		T	`<time.h>`	C11
`TIME_UTC`	Indicator for UTC time in `struct timespec`	M		`<time.h>`	C11
`timespec_get()`	Read nanosecond time		(·)	`<time.h>`	C11

Macros with names matching ^TIME_[A-Z] might be added to <time.h>.

<time.h> defines a type struct timespec, which represents a time duration in nanoseconds.

Fields of `struct timespec`
Field	Meaning
`time_t tv_sec`	Whole seconds
`long tv_usec`	Nanoseconds

How can time_t be used here, if it's not necessarily a time in seconds? If it's not being used that way, what's the point of equating it with a time_t?

#include <time.h>
int timespec_get(struct timespec *tsp, int base);

The function timespec_get gets the current calendar time, and assigns it to *tsp. The only portable value of base is TIME_UTC.

Functions making use of `struct timespec`
Name	Description			Source
`cnd_timedwait()`	Wait on a condition variable for a limited time	?	(·)	`<threads.h>`	C11
`mtx_timedlock()`	Try for some time to lock a mutex	?	(·)	`<threads.h>`	C11
`thrd_sleep()`	Suspend current thread	?	(·)	`<threads.h>`	C11