For both process and children times, the structure breaks down the time by user and system time. Since the OpenVMS system does not differentiate between system and user time, all system times are returned as 0. Accumulated CPU times are returned in 10- millisecond units. Only the accumulated times for child processes running a C main program or a program that calls VAXC$CRTL_INIT or DECC$CRTL_INIT are included. On OpenVMS Version 7.0 and higher systems, the times function returns the elapsed real time in clock ticks since an arbitrary reference time in the past (for example, system startup time). This reference time does not change from one times function call to another. The return value can overflow the possible range of type clock_t values. When times fails, it returns a value of -1. The Compaq C RTL uses system-boot time as its reference time.