According to the documentation:

tc = now()

where

tc: number of milliseconds from 01jan1960 00:00:00.000, unadjusted for leap seconds [emphasis added]
Yet, in practice (see below), it seems to be truncated to the nearest second.

.ÿ
.ÿversionÿ17.0

.ÿ
.ÿclearÿ*

.ÿ
.ÿlocalÿline_sizeÿ`c(linesize)'

.ÿsetÿlinesizeÿ80

.ÿ
.ÿmata:
-------------------------------------------------ÿmataÿ(typeÿendÿtoÿexit)ÿ------
:ÿmataÿsetÿmatastrictÿon

:ÿ
:ÿvoidÿfunctionÿMS()ÿ{
>ÿ
>ÿÿÿÿÿÿÿÿÿrealÿscalarÿnow,ÿthen
>ÿ
>ÿÿÿÿÿÿÿÿÿthenÿ=ÿnow()
>ÿÿÿÿÿÿÿÿÿstata("sleepÿ250")
>ÿÿÿÿÿÿÿÿÿnowÿ=ÿnow()
>ÿ
>ÿÿÿÿÿÿÿÿÿassert(nowÿ==ÿthen)
>ÿ
>ÿÿÿÿÿÿÿÿÿrealÿscalarÿindex
>ÿÿÿÿÿÿÿÿÿforÿ(index=1;ÿindex<=2;ÿindex++)ÿ{
>ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿprintf("%tcHH:MM:SS.sss\n",ÿ(now,ÿthen)[index])
>ÿÿÿÿÿÿÿÿÿ}
>ÿ}

:ÿ
:ÿMS()
20:47:40.000
20:47:40.000

:ÿ
:ÿprintf("%3.0f\n",ÿclockpart(clock("00:00:00.125",ÿ"hms"),ÿ"ms"))
125

:ÿ
:ÿprintf("%3.0f\n",ÿclockpart(now(),ÿ"ms"))
ÿÿ0

:ÿ
:ÿend
--------------------------------------------------------------------------------

.ÿ
.ÿsetÿlinesizeÿ`line_size'

.ÿ
.ÿexit

endÿofÿdo-file


.

Is there any way to obtain full-precision clock time from the Mata function now(), or by any other way in Stata short of resorting to Python or Java?

Environment: Windows 10 Pro, 64-bit, current update