title: what is the sub-second format in sox audio duration?
body: <p>Been searching, and I can't seem to locate the units used in the duration of an audio file when requesting information about the file from sox. I'm using "sox --i file" to generate the info.</p>
  
  <p>The duration string is like "00:00:05.51" in one file I have, but looking at online examples as I try to find this format I see duration strings like 00:00:19:986. What is that last 986? Is the format of sub-seconds in 1000's? </p>
  
  <p>Seems anyplace referencing duration simply skips any mention of the format for sub-seconds. </p>