#### 25.1.4.4 Seconds

One function, sleep, takes its argument as a non-negative real number of seconds. Informally, it may be useful to think of this as a relative universal time, but it differs in one important way: universal times are always non-negative integers, whereas the argument to sleep can be any kind of non-negative real, in order to allow for the possibility of fractional seconds.

      sleep

      Figure 25–8: Defined names involving time in Seconds.