Quoting from <https://srfi.schemers.org/srfi-19/srfi-19.html>:

---

A time object consists of three components:

* Time type, a symbol representing the time system representation used.
The constants TIME-TAI, TIME-UTC, TIME-MONOTONIC, TIME-THREAD,
TIME-PROCESS, and TIME-DURATION must be provided for these symbols.
Implementations should provide constants for time type extensions.

* Second, an integer representing the number of whole seconds from "the
epoch."

* Nanosecond, an integer of the number of nanoseconds in the fractional
portion. Although a time object has nanosecond precision, clocks may
have a lower resolution.

---

Although SRFI 19 mandates a ton of other stuff, the timespec object in
SRFI 174 seems to be an exact duplicate of a SRFI 19 time object. SRFI
19 just has an extra time type field.

Also procedures:

* make-time type nanosecond second -> time
* time? object -> boolean
* time-nanosecond time -> integer
* time-second time -> integer